Pentium 4 Processor is much powerfull than a Celeron Processor.You can read a very interesting article on How stuff works about the difference between a P4 and a Celeron.

The most important differences are:
-Celeron processors have less cache memory than Pentium 4
-P4 chips are more faster than Celeron.
-P4 has about 30% more BUS Speed than Celeron processors