CVS and Subversion Differences
In CVS, revision numbers are per file. CVS uses RCS (Revision Control System) as a backend, and each file has a corresponding RCS file in the repository. The repository is roughly laid out according to the structure of your project tree.
In Subversion, the repository looks like a single filesystem. Each commit results in an entirely new filesystem tree, so the repository can be likened to an array of trees. Revision 62 would refer to a particular tree - the way the filesystem looked after the 62nd commit.
In CVS, you may talk about 'revision 4 of source.c.' In Subversion, you would say 'source.c as it appears in revision 4.' In CVS, revisions 3 and 4 of source.c are always different. In Subversion, it's quite likely that source.c was not changed between revisions 3 and 4.