Outwardly I don't see any differences at all but I've never had a Charger 651 in front of me. I own a Project 651. Maybe it was an east coast/west coast thing, I don't know.
The alphabet soup is Japans' model ID system. They only came here like that for the first couple years, then some got here with both the Japanese ID and a new American name/number on them, then the Japanese ID was dropped and just the American ID would be on the machines. Sometimes it was just a number and sometimes it was a number and a name.
Cari