The M60 was a design that appeared later on the cold war, and was not an exact development of the earlier patton series, but rather a product-improved descendant of it. it was almost completely different, mounting a new 105mm rifled tank gun, having up to 155mm of armor (with no ERA) and a new, much stronger, engine. It was deeply modernized and very well-accepted in the international market (despite its irreversible design flaws, such as its very high profile) and is in service with many armies around the world today.
M46: the basic and first verison of the patton series, considered a medium tank. Very similar in appearence with the previous M26.
M47: a modernized M46, with most of the differences being in the fire control systems and the slightly redesigned turret.
M48: the final version of the early patton series, widely used in combat and active in armies around the world up to today. Not much different from the M47.
M60: the beginning of an almost entirely new series of designs, that have been modernized to fit today-quality. Armed with the american version of the british L7 105mm rifled tank gun.
M60 A2: it was an modified M60, given a new turret and mounted an 152mm gun and was able to shoot missiles. Not in service for long