What is the difference between 1st 2nd 3rd gen ipods nano 4gb help please?

You can get the 3rd gen (plays video, has big screen, new interface) for $199 8GB from Apple. 4GB 2nd or 1st is a rip off. Any 4GB for $199 is a rip off. Get the 3rd gen. It looks like a square kind of. Do not get the tall skinny ones, thats not catching up on technology, thats just stupid.