Computer Science vs Software Engineering: Everything You Need to Know About Differences, Courses, and Careers
Still not sure whether to pick computer science or software engineering? Let's roll up our sleeves, peek behind the curtain, and get to the bottom of what REALLY separates (and connects) these two university majors. Trust me—if you've ever googled “computer science vs software engineering,” you’re about to get answers no algorithm has ever served up!
Defining Computer Science and Software Engineering: Where Theory Meets Build
Let's start at ground zero: what do “computer science” and “software engineering” even mean?
What is Computer Science? The Theory League
Search around, and you’ll find computer science described as “very theory based,” practically a mystical cousin of pure mathematics. This isn’t just a label—it’s the heart of the major. In CS, you explore algorithms (the secret recipes behind your favorite apps), data structures (think: how info is packed away for speed), discrete math (set theory, combinatorics, the good stuff), and the theory of computation—a field that asks, “What problems can computers solve, and how fast can they do it?”
Computer Scientists are often the ones at the whiteboard, not just coding, but inventing entirely new approaches for computers to think. Want to design a neural network that beats humans at chess? Dreaming about being the wizard who makes AI see and understand the world? Fascinated by the secrets of cybersecurity, keeping hackers at bay with the latest cryptographic magic? Or how about exploring quantum computers—machines so futuristic even most of Silicon Valley’s still catching up? That’s computer science in action.
Consider Jane, a CS grad who ended up in research. Her “9-to-5” involves designing smarter AI for medical imaging—teaching computers to spot tumors better than humans do. She’s NOT just coding another website; she’s helping reinvent how hospitals work.
Software Engineering: Architecting Real-World Systems
Now, picture software engineering as the ultimate builder’s major. While computer science might invent a super-fast sorting algorithm, software engineers grab that tool and use it to build skyscrapers out of code: think Microsoft Office, World of Warcraft, or top-tier antivirus programs. We’re talking millions of lines of code, sprawling teams, project deadlines, budgets—the works.
There’s no “just start coding” chaos. Software engineers are masters of planning: gathering user requirements, mapping out the stages of a project (aka the “software life cycle”), making important trade-offs between speed, usability, and features, then testing everything, thinking about how to scale for a billion users, and making sure the end product won’t turn into an unusable mess.
Imagine Sam, a software engineering grad assigned to launch a new messaging platform. He doesn’t need to invent his own encryption—he uses tried-and-true methods designed by computer scientists. But he HAS to turn the boss’s wild vision into a real app people love to use, stay organized with his team, keep everything bug-free, and adapt when users suddenly swarm the app after a viral TikTok. THAT’s software engineering.
Telling Them Apart—Except When You Can’t
Yes, the definitions sound tidy: computer science rules the world of theory and invention, software engineering brings those inventions into the real world. But in reality? That border isn’t just blurry, it’s practically invisible. At top tech companies, you’ll find grads with both majors working side by side, often in the very same job titles. The typical job listing? “Degree in Computer Science or related field.” The “related field” here could definitely be software engineering or computer engineering.
That means your future isn’t sealed by the title on your diploma. Curious why? Many research-y “pure” computer science jobs (such as inventing new cryptography or AI) call for a master’s or PhD—so, most undergraduate CS majors? They typically wind up in... you guessed it, software engineering jobs at Google, Facebook, Amazon, and friends.
College Courses: What Do You Actually Study?
Baffled by the endless lists of courses in each major? Let’s turn those abstract definitions into real classes, real assignments, and—honestly—some real headaches. For easy comparison, let’s use Cal Poly San Luis Obispo’s curriculum as our example playground.
The Shared Stuff (Classes EVERYONE Takes)
- Three programming courses (building your coding foundation: syntax, logical thinking, core languages)
- Discrete mathematics—where you meet proof techniques and set theory
- Computer hardware basics (because, yes, you’ll care about how metal turns into Minecraft graphics)
- Systems programming (digging into C, pointers, OS-level concepts)
- Algorithm design—a serious course full of Big O notation and sorting magic
- Programming languages (not “Spanish” and “French,” but Java, Python, Lisp—why do we need so many?)
- Professional responsibilities (Think: legal issues, code ethics, safety. Yep, you’ll talk about NOT coding like a supervillain.)
Here’s the kicker: these nine “core” courses are taken by BOTH computer science and software engineering students. It’s not just theory for one and building for the other—both sides get a heavy dose of each!
For example, as an undergrad, I sweated through those algorithm classes with future software engineers. In our team project, we launched a simple “Find My Bus” web app—my buddy coded the data structures, I worked out the logic, and we realized, “Whoa, our education’s basically twinsies.”
The Special Sauce: Classes Unique to Each Major
What Makes Computer Science...Computer Science?
- Computer Architecture: Dig into processors, memory hierarchies, and why dad’s old CPU is so slow. Expect detailed labs, hardware diagrams, and code that sometimes makes your brain melt.
- Operating Systems: Peek under the hood at Windows, MacOS, and Linux. Learn how your computer multitasks, schedules jobs, and keeps apps from fighting each other. Labs galore!
- Theory of Computation: The mind-bender. Why can’t computers solve every problem, even with infinite memory? Get ready for lots of proofs, thinking like a philosopher, and the infamous Turing Machine thought experiments.
- Second Programming Languages Course: Sometimes you need even more language skills for super-advanced coding challenges.
Let’s walk through an example: In Theory of Computation, you’ll discuss the finite state machine using a simple two-story elevator. The elevator has two buttons (up/down) and two states (first/second floor). Push up on the first floor, you move; push down, back to one. Try pressing down at the bottom—nothing happens. Computer scientists swap “floors” with “state A” and “state B,” and replace real buttons with ones and zeros, building a mind model for how computers react to basic inputs with limited (or nearly no) memory. Suddenly, you’re not just debugging code—you’re answering deep questions like: “Can this bare-bones machine tell if there’s an even number of 1s in a stream?” (Spoiler: yes, using just “even” and “odd” states!) But if you want the actual count? Not happening—welcome to a real limitation of some computers!
Take it to the next level: what if your machine had unlimited memory (the so-called “Turing machine”)? Could it solve everything, like predicting if a program would ever stop running? That mystery is part of the magic (and headaches) CS majors face.
Software Engineering Courses: Where the Planning Happens
- Software Engineering (third year): Start with definitions: end-user software (for regular folks), systems software (which supports stuff under the hood), and embedded software (the code running your smart fridge or car). You’ll get introduced to roles like testers, analysts, and more—not just coders!
- Hands-On Projects: A big twist: SE features quarter- (or semester-) long team projects, not just labs. For instance, you might have to prototype a Grocery App’s GUI—making it user friendly, NOT just fast.
- User Centered Interface Design: Suddenly, you’re in the mind of the end user. Is your calendar app actually pleasant to use? Can a grandma (or a fellow engineer) figure it out without crying? Expect to write reflections on what works, what’s frustrating, and create storyboards explaining your vision for a productivity app—no coding required.
- Project Planning Classes: Less about hardcore code, more about teamwork, documentation, and deadlines. Like prepping for a job at a big tech company—meetings, task lists, surprises, and staying sane.
Classic story from the front lines: I had a stint at a small software company, assigned to spice up an app’s interface. The old system? Users typed input commands in a clunky terminal. The upgrade? A sleek GUI—with boxes for values. Suddenly, sales people (not just hackers) could use the tool! That’s what these courses prep you for—thinking like a user, not just a coder.
Math Requirements: Is It All Calculus, All the Time?
Good news, math fans (and math-fearers): the required math for CS and SE is nearly identical. You’ll both wrestle with discrete math, calculus, and logical thinking. BUT, at some schools (like Cal Poly), only software engineers must take the full chain of calculus-four-and-five, including multivariable calculus. Computer science majors can occasionally skip those later rounds, making their math load a smidge lighter—unless you pick the harder electives!
Curriculum: Labs vs. Projects, Real World vs. Theory
Here’s another major difference. Computer science majors usually complete weekly or bi-weekly labs, frequently tying in new theory with hands-on coding. Software engineering majors, in contrast, push through quarter- or semester-long team projects. These projects mirror the chaos (and fulfillment) of a real job—they demand teamwork, documentation, and hitting client goals. You get fewer “Labs 1-15,” more “Plan, build, ship, present to classmates, and pray the demo gods are kind.”
Can You Swap Majors? Choose Electives? YES!
Here’s a plot twist for you: at many universities, software engineering isn’t even offered as a separate major! “Just pick Computer Science,” say the advisors, “and take the right electives.” Why does this matter? It means you are NOT boxed in. CS majors can enroll in SE-style project management classes, and SE folks can request theory-intensive courses if they’d like. Lots of elective freedom.
Whatever path you choose, you can always tweak it to fit your vision—whether that’s AI, security, apps, games, or something no one’s invented yet.
So, Which Is “Better”? (Spoiler: No One-Size-Fits-All Answer)
Here’s the truth bomb: since the two paths overlap nearly 90%, picking one over the other rarely locks you out of any particular job. The tons of shared core knowledge, the ability to choose electives, and the blurry line between industry roles means you should pick based on what kind of problems you love. Into theory, abstraction, and inventing new ways for computers to think? CS is your home. Fired up by shipping products with teams and making life better for real people? SE has your name all over it.
Lucky for you, there’s no disaster looming if you choose one and later decide the other matches your dreams. You can swap focus with a few strategic electives—and friends who did so have landed everywhere from Silicon Valley to indie game studios.