Originally Posted by Del Boy
It's to do with Intel's tick-tock policy. These are all "Core" chips. Ticks are small changes, generally a shrink in die size / fab process. Tocks are bigger changes, generally architecture ones.
Pentium 4 / P6
Tick - Presler/Ceder Mill 65nm
Tock - Conroe 65nm
Tick - Penryn 45nm
Tock - Nehalem 45nm
Tick - Westmere 32nm
Tock - Sandy Bridge 32nm
Tick - Ivy Bridge 22nm (actually was marketed tick plus)
4th GenTock - Haswell
Tick - Broadwell 14nm
I actually think it should be 5th Gen... because Yonah was the original 1st Gen.
Hope that clears it up for you!
But they called Sandy "2nd generation" and Ivy "3rd generation"?
I'm quite sure they simply included Westmere in the "1st Generation" category for whatever reason.