Off the top of my head:
AK-47 Type I: First production AK type, used stamped and milled components.
AK-47 Type II: Transitional milled AK-47.
AK-47 Type III: Classic milled AK-47.
AKM: Stamped receiver AK with weight-saving features.
AKMS: Same as above with underfolding stock.
AK-74: 5.45mm AKM replacement.
AK-74N: Same as above with rail to mount optics.
AKS-74: Same as AK-74 with sidefolding steel stock.
AKS-74N: Same as above with optics rail.
AKS-74U: Commonly called the "Krinkov."
AK-74M: The modern-issue assault rifle; all the features of the AKS-74N w/poly sidefolding stock.
AK-105: AK-74 carbine.
AK-103: 7.62mm version of the AK-74M.
AK-104: Carbine version of the AK-103.
There are also the RPK, RPK-74 and their variations with optics rails and folding stocks.
This is the quick and dirty list. There are infinite details that go with these.