Why do smartphones have up to eight cores but many laptops still only have two?

Question

I have been looking at buying a new smartphone as well as a new laptop. What has struck me as odd is that many smartphones now have quad cores or even octa cores, yet many laptops still only use dual cores, not even going to quad core in many cases. Can someone explain to me why phones are getting more cores than laptop? Im not a desktop computer user, Im guessing they commonly use quad cores.

I guess this leads to another thing that has been bugging me; what is the difference between a mobile processor and a normal processor at the same clock speed? What causes the performance difference. Specifically I am worried about the new MS Surface Pro 4, which has been predicted to use a Broadwell M processor. If it is using a mobile processor, would it be worse off than the Surface Pro 3, which uses a normal processor?

Cheers guys

Answer 1

Laptop (And certain desktop) CPUs simply have stronger cores. So a 1GHz desktop/Laptop CPU that has double the core performance of a 2GHz mobile will easily sweep the floor with the mobile CPU.

source(there are also more posts on the topic here)