what's the differences from free and pro versions?

I was thinking in play a little with game development, just for fun, and I found unity. Looking in the site I noticed that there are 2 versions: free and pro (paid). What I didn’t find was the differences.
What does the pro version have that the free version doesn’t? What’s better in the pro version?
Thanks for the help.

Bam!

I’ve been using the free version of Unity for over a year now and so far there are only a couple of things that I really wish I had.

A: The profiler. This helps you figure out where the bottlenecks in your code are. Optimizing can be a real pain when you have to use process of elimination.

B: Postprocessing effects. I haven’t needed this too much because I do 2d stuff but it would certainly be nice to have. If you are doing 3d development it can be hard to get a nice polished look without these.

Of course the monetary restrictions are potentially a big deal but since you are doing this for fun it’s not a concern unless you happen to “make it big” at which point you could probably afford to buy the pro version.

EDIT: One big one I forgot is the custom splash screen. It’s a pretty annoying requirement of the free version.