x86 series -
Intel
8086
8088
80286
80386
80486
80486DX2
Pentium 1
Pentium 1 MMX
Pentium 2
Pentium 3
Pentium 4
Pentium 4 HT
Pentium D
Core 2 duo, Dual core
Core 2 Quad
Core i 3, 5, 7 series - up to date
After Core series , they sticked to the same brand name but CPU generations evolved.
Core i3,i5 and i7 CPUs have 6 generations.
Core i3, i5 , i7 1st generation - Nehalem (code name)
2nd Generation - Sandy Bridge
3rd Generation - Ivy Bridge
4th Generation - Haswell
5th Generation - Broadwell
6th Generation - Skylake ( latest processor line up)
1st, 2nd, 4th and 6th generations have different microprocessor architectures just like Pentium 1 differs from Pentium 2.