There are more types than just Intel Celeron(R) and Pentium(R). Celeron(R) isn't as fast and powerful as Pentium(R).
Well, actualy lets say I have Intel Celeron(R) CPU 2.40GHz (Which I do have) and Intel Pentium(R) CPU 2.40GHz. The Pentium would be much better and faster than Celeron at the same speed.