Universal Features:
-Music plays constantly with no silent periods
-Shuniji, Dragon Fish, and Axolotl have been added
-Creative, Survival, Menu, and Water music plays interchangeably
-End and Boss play interchangeably
-Dog plays after the Cat music disc (Easter egg from Console Edition)
-All songs play at 0.5 volume
-Music disc music will still play from the jukebox regardless of setting chosen below

Pack Settings:
Default - This is the normal setting for the pack with all the features listed above.
No Water Music - This is the exact same as Default, but without Shuniji, Dragon Fish, or Axolotl.
Old Music - This uses the music from before the 2013 Music Update. It doesn't use Creative, Water, Nether, End, Credits, or Menu music.
Old Music+ - This is almost the same as Old Music, the difference being that it still uses Nether, End, and Credits music.
Total Mix - This lets any music, including Credits, End, Boss, Nether, Water, Menu, Survival, and Creative play at any time.