Sempron = Celeron?

Sempron are the AMD equivalent of the Intel Celeron, or so I've heard, but are they the same level of quality (or lack thereof)? I've never had anything but problems with celerons, and I'm a bit wary of buying a sempron because of the way they've been compared to the celeron. is this justified?
if they're alright, it'll save me a lot of money... but I'd like to be sure.

Semptron = Old AMD XP, nothing reduced (sutch as cache), some new stuff might have been added (as overheating protection).

Celeron (differs between models) = old arcitectures, reduced cache size.

Anyway, Semptron > Celeron