Agile v. Traditional Software Development: A Picture Paints a Thousand Words

Every so often, someone will claim you can’t articulate the difference between Agile and traditional software delivery methods. So, let’s give it a go—and throw in an image to drive the point home.

Horizontal Design: The Traditional Approach

In traditional software development, we tend to follow the good ol’ Software Development Life Cycle (SDLC), and it’s an all-or-nothing affair. Development often happens in horizontal layers. Some of these layers might even be fully functional and testable—sounds promising, right? But they’re often dead ends.

For instance, take a project where we start with the foundation. Let’s say it’s the database. The database could be fully implemented, loaded with data, and accessible via some SQL interface. So far, so good. But can I release it to the public? Nope. Without the user interfaces and business logic on top, that database isn’t going to see the light of day.

This kind of horizontal layering means that, despite some components being ready, the project as a whole stays under wraps for ages. That’s why, in traditional methods, it’s easy to end up demoing front-end functionality—just the tip of the iceberg. Inevitably, stakeholders will ask if this means we’re nearly done. I can’t tell you how many times I’ve had to explain, “No, we’re still miles away.” It’s all good and well having a shiny front end, but until it’s hooked up to everything else, it’s just a pretty picture.

Vertical Slices: Agile to the Rescue

Now, compare this to Agile. The goal here is to release “working software” as soon as possible. We’re after early value realisation and deferred expenditure.

In Agile, development happens in vertical slices. Think of it as delivering thin, functional layers that span across the entire project, from the user interface down to the database and business logic. If I can deliver a functional slice, I can already start to generate value. Maybe that value is learning—“Is this what people actually want?”

Here’s where Agile shines: if the answer is “no, nobody wants this”, I’ve learnt the lesson without wasting heaps of time, effort, and cash. In traditional development, I might not get that same feedback until much later, when I’ve already sunk loads of resources into it.

The Minimum Viable Product (MVP)

Let’s say in Agile, each slice represents a sprint. Maybe I need a few sprints to release a Minimum Viable Product (MVP). Even so, the potential for early value realisation is clear. I can put a few slices out into the market, react to the feedback, and, if needed, pivot quickly.

Suppose one of those slices (let’s call it the red slices) represents unwanted functionality. In Agile, I can drop it with minimal fuss and expense. With traditional methods, the money has already been spent, and now I might have to spend more to undo it.

Agile: Fail Fast, Adjust Faster

In Agile, the mantra is to fail fast. If we’re going to mess up, we want to know early and course-correct. Traditional development? It’s like building a house in layers, only to find out at the end that the homeowner didn’t want a house at all, but a treehouse.

Agile gives us that flexibility to learn, adapt, and move forward, while traditional methods often lock us into a path with fewer opportunities to change direction.