It's been a while since I've checked, but...
A Celeron used to be nothing more than a normal Pentium with the L2 cache removed or reduced.
Intel used to make one processor, then market it ( with different clock speeds / cache ) as a number of different processors. They probably still do - which is why Pentiums are usually stable when overclocking.
So yeah, a Celeron is a "starved" Pentium.
For more info have a look at the review section of www.hardocp.com
- they'll probably have one specific to the processor you're considering.