Seriously, replace some FFVII characters with some of the peeps from FFVI and you'll see how similar they are.

Cloud - Locke
Aeris - Celes
Tifa - Terra
Sephiroth - Kefka
Shadow - Vincent

I haven't played enough of VII to compare other characters, although I have started it just recently. Also, if Aeris is really Aerith, then does that mean Celes is really Celeth?