So who can tell me what the differance in nameserver versions is?

Assuming you're reffering to the software that runs the nameserver,
like with any software the differences are usually bug fixes and improved
functionality. Open source software usually has documents attachaed as to
whats been changed between versions.

Most servers are running some version of Bind. The official site is here and can provide more info on what changed with each version:

http://www.isc.org/index.pl?/sw/bind/