I have been researching Breakaway and Getaway - the two new Norwegian Ships and there are more differences than you might think.
I think the itinerary for Getaway offers you a lot more opportunity to use the Waterfront Walkway. Especially at night when the tropical air cools down, or during the day in the Winter. Breakaway (sailing from NY) will be pretty cold many of the days.
Getaway has different entertainment. The main show is "Legally Blonde" - but also the ship does NOT feature Second City (they have a different provider of standup comedy - an LA-based agency).
It also does not have Cirque Dreams, instead they have the Illusionarium, a place for magic and other mysteries.
They do not have Legends at Sea - it has been essentially replaced with "Burn the Floor" a dance review with professional dancers.
Getaway has "The Grammy Experience" - which we are not yet sure about, how it will manifest. They mention performers and items related to Grammy award winners.
Breakaways entertainment is pretty much the same as "Epic" with the exception that "Blue Man Group" has been replaced with "Rock of Ages" a Broadway show about the hair bands of the 80s.