Maui Ocean Club, which we refer to generically as MOC, consists of three towers, which have some notable differences between them, covered elsewhere.
MMO refers to Interval International's code for the original building, Marriott Maui Ocean Club, which was built as a hotel and converted to timeshares.
MM1 refers to Interval International's code for the two recently constructed towers (2007 and 2009) which are Lahaina Villas and Napili Villas.
Both MMO and MM1 are great properties. I hope that helps.
Best,
Greg