The first paragraph of
http://www.anandtech.com/show/2549
G80 = the first generation of the GT architecture.
G92 = the second generation of the GT architecture.
Each of them has a family and also belongs to the GT achitecture family.
Fermi architecture
GF100 = the first generation of GF architecture
GF104/106/108 = the second generation of GF architecture
Again, i don't see the constructive reasoning on picking the use of the word "generation", and to defend myself may lead to more nonconstructive argument. I will stop here on this particular matter.