People often ask for "a website" when what they actually need is a tool their customers can use. The two aren’t the same project, and knowing which one you need before the first call saves everyone time.
An informational website and a web app can look identical at a glance, both open in a browser and can share a similar design. The main difference is what people use them for.
A website tells; a web app does
A website's job is to show what you do and get someone to take the next step, call you, fill in a form, request a quote. The content is mostly the same for every visitor. A web app's job is to let someone do something specific: book a slot, log into an account, run a calculation, manage their own data. The content changes depending on who's using it and what they're doing.
Signs you need a website
- You mainly want people to find you, understand what you offer, and get in touch.
- The content is roughly the same for every visitor.
- Visitors don't need their own accounts; your main content task is updating text and images, alongside technical maintenance.
Signs you need a web app
- Users need to manage their own data, bookings, or other personal content, possibly after logging in.
- The site helps people complete a task, for example, making a booking, running a calculation, or processing information across several steps.
- The idea is closer to "a tool" than "a brochure," even if it's for your own internal use rather than the public.
Where e-commerce and booking systems fit
Online stores and booking systems are types of web app: they manage orders, stock, or available appointments, and often handle payments too. That makes planning and pricing more involved than for a simple informational site. You can also add an existing booking or shopping service to a website, so you don't always need everything built from scratch.
Not sure where your idea fits? That's a completely normal starting point, describing what you want people to be able to do on the site usually makes it clearer.