Differences between core i3 and i5 and i7

Core i3
* Entry level processor.
* 2-4 Cores
* 4 Threads

Core i5
* Mid range processor.
* 2-4 Cores
* 4 Threads
* Turbo Mode (turn off core if not used)
* Hyper-Threading (efficient use of processor resources)
* 3-8 MB Catche
* 32-45 nm Silicon (less heat and energy)

Core i7
* High end processor.
* 4 Cores
* 8 Threads
* Turbo Mode (turn off core if not used)
* Hyper-Threading (efficient use of processor resources)
* 4-8 MB Catche
* 32-45 nm Silicon (less heat and energy