Yes any cruise ship casino is much worse for payouts then a land based one. I know the HAL ships even have something posted about meeting the minimun Neveda State gaming laws.
Slot Machines payout in the 85-88% range, Video Poker maybe 90-92%. Whereas my favorivte place for land based gaming Reno, Slots usually pay out around 95% and Video Poker 98%
Vegas strip casinos are also very tight, better chances are off strip or downtown.
Good Luck,
Paul