2009 Lincolns

just to break it down

4 different circulation strike in P and D mints (8)
4 different mint set strikes(Satin matte) in P and D (8)
4 different proof strikes in S mint (4)

there's your 20 different coins

And the ones in the Mint Sets are all Copper. Normal ones for circulation are the Zinc ones. For now it's rather simple to know which is which but in the future as those Mint sets are broken up and coins slip into circulation, going to be fun trying to tell which is which.
Supposedly each type is supposesd to represent Lincoln's life on the reverses. The first shows a Log Cabin, second shows him possibly plaing around with some wood (carving out a story to tell his wife why he wan't working), Third shows him in a legislative appearance and finally a Whitehouse where he is supposed to be after he wins the election.
So now after all that the Mint further improved ther reverses by sticking a what could be King Arthur's Shield on the reverse. Might be to honor the British since so many are retaking our country starting with the Beatles.