There are the 3 regular broadway-style shows.
DCL also has some other "big theatre" shows (Once Upon a Song, for example) that they bring out on the really long cruises. And they have special performers, and artists.
There is a different show every night.
On our recent TransAtlantic we had:
Night 1 - All Aboard: Let the Magic Begin
Night 2 - Walt Disney: The Dream Goes On
Night 3 - Voiceplay (accapella vocal group)
Night 4 - Movie - Captain America
Night 5 - John Charles (comedian/musician)
Night 6 - Junnk
Night 7 - Trigg Watson (magician/comedian)
Night 8 - Tangled: The Musical
Night 9 - Mandy Gonzalez (Disney Theatrical)
Night 10 - Liverpool Legends (Beatles tribute group)
Night 11 - Susan Egan (Disney Theatrical)
Night 12 - Twice Charmed
Night 13 - PremEAR at sea - Alice Through the Looking Glass
Night 14 - Disney Dreams: An Enchanted Classic