You answered your own question.....if they are completely different cars then the parts, seats, electronics, engines, etc. WON'T FIT! :chairshot:
I bought a new ES250 in 1991 and when I traded it in, in 1994 for an ES300, I compared all the different parts.....they were WAY different.
If you're looking for new wheels for an ES250 try looking at custom wheels for a 1991 Camry. ;)