Isn't web development and web design the same thing?

They are two different stuffs, here's a brief explanation of them both.

Web design is about the layouts and graphics of the website. In short, its more on what you can see in a website.

Web development is the whole process of making a website in which web design is part of the process. Along with the web designing are web content development, client/server side scripting and more.

Actually it's 2 completely different things. They may seem similar, and people may have similar skill sets, but there is a line of distinction.

Web Design: Creating Graphics, Layouts, working with the client to achieve the "look" of the website. As one of the commenters mentioned it is part of the process.

Web Development: The previous commenter mentioned that it is the entire process of creating the website. Sure you can say it's that, but really (as a web developer) it's much simpler than that ... Web development is the 'scripting or the programming' that is associated with the website.

Here is an example:
The last few places I have worked, the Web Designers in our creative group, built great looking websites. But they were unfamiliar with the how to add in things like Form validation, javascript, etc.

While the web developers built complex working websites, that required massive databases, and thought about things like how can we squeeze a bit more traffic through our servers that were working close to 100% because we had over a 1,000,000 transactions a second. You ask any of them to design something with a user interface, and you'd come back with things that looked like they were designed by a second grader.

Some people have great cross over skills, and those people usually don't have depth of knowledge in one area in particular. Trust me when I say, they are completely different skill sets. It really depends on what you're looking to build that will determine which type of person you should hire.

Are you looking to build something that requires a lot of business logic? Or do you require a simple opt-in form?

Think of it this way ...
Web Design - This person would design the form.

Web Development - This person would tie the form to a database or to an API that would communicate to your mailing list to add the person, or whatever you require it to do ...

Hope that helps.

different,

in concept of MVC (model, view, control)

web design: view
setting about what will user / visitor view

web develop: control & model
setting how user / visitor will view