1. What is CVS?

CVS is a version control system. Using it, you can record
the history of your source files.

2. What is the difference between CVS and CVSNT?

CVSNT is the Windows OS version of cvs.

From a SCM perpective, they share similarity in purpose,
commands including syntax and functionality.

Both are freeware.

Installation is a breeze for anyone who has a working
knowledge of *NIX and Windows.

Both can be accessed through clients.

Yes, I know i was asked for differences.

I answered with a view to help out any desperately seeking
hu SAN who landed here.

3. What operating systems does Subversion run on?

Surely for Windows & Unix

4. Tell me Does Subversion have changesets?

No