Workspaces vs Codepen.io

Great question!

You can use both! Codepen is awesome, we love it at Treehouse. Codepen, right now takes a simplified model of coding, where you just give it a snippet of html, css, and javascript, and it creates a basic page.

What we are doing with Workspaces is providing a development environment closer to what you use day to day. You don't just use snippets of code, but real files and folders. You can have multiple html pages, and stylesheets and have a multipage site in Workspaces.

This is just our first version of Workspaces, and we're going to be adding quite a bit to it. For instance, right now it only supports basic static websites, but we have plans to expand it's capabilities a lot in the future.

The other thing we are doing is integrating our courses with Workspaces. For instance if you take the How to Make a Website project, you will be able to follow along and build the whole site in Workspaces, as Nick does it in the video.

Codepen isn't setup for building multi page sites like Workspaces is. On the other hand, Workspaces isn't set up for sharing, Codepen has quite a few nifty realtime demo features.

So those would seem to be the major differentiating factor.