To get a little more technical and expanding upon tcrosley answer (which is good btw), there are two ways a processor can really go. Either a company will:
- Invest into a higher speed core for the processor
- Invest into more cores of the same speed
Intel has taken the higher speed core course. They have invested in having much faster processors over just adding more cores (like AMD).
Because of the x86 architecture and its history, many many many programs do not take advantage of the multiple core (eight-core) that AMD offers, which Intel has realized. Their investments have increased in better and smaller transistors which allow for better cores.
While the multi-core is great, there are not many applications that utilize all of them but on the off chance you need them, Intel has included multiple cores in the processors for PCs as well.
All in all, this is a huge result of the higher revenue of Intel
With all that said, there are so so so many factors that go into designing the die, some that are not apparent when looking at the specs of the processor as a whole.