Intel stopped selling Core 2 Duo and Core 2 Quad in 2010. Core is the new range of Intel processors.
Core i3:
* Entry level processor.
* 2-4 Cores
* 4 Threads
* Hyper-Threading (efficient use of processor resources)
* 3-4 MB Catche
* 32 nm Silicon (less heat and energy)
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)