We have only been to RCL's Labadee, so can only speak to that compared to Castaway....
- Food at the free buffets were similar on both. Chicken, burgers, salads, cookies, etc.
- No "adult beach" on Labadee. All beaches open to all age groups
- Labadee had a beach that was for suite guests only
- Labadee was more spread out than Castaway. There were more beaches and the beach areas varied in offerings and type. Columbus Cove was sandy and water was fairly calm. Adrenaline includes more activities, but is rocky with more waves.
- More variety of rentals on Labadee, including cabanas, bungalows, beach beds and clamshells.
- Loungers and umbrellas are not pre-set as they are on Castaway. Island workers will set them up for you, and they expect a tip.
- The day we were there, there was live music on the beach, and the musicians were selling their CDs.
- There are more vendors on Labadee selling crafts, hairbraiding, etc. Some are quite aggressive, others more laid-back.
- More 'thrilling' activities on Labadee - zip line, mountain coaster, inflatables in the water, etc.
- More of an atmosphere thing, but Labadee is fenced and gated. You won't see any guards, but they are there somewhere.
- Labadee does have a pier, so you can walk to the ship like at Castaway.
Those are the main things I can think of off the top of my head....