I’m more a Royal guy than
DCL but I’ve been on both Harmony and Fantasy so I’ll try and talk about both.
The first thing is something I’ve finally figured out and I’m not sure why it took so long - DCL is more about bringing Disney to a ship than having a cruise experience with some Disney built in. Royal is much more like a traditional cruise in that respect. You’re on a boat, and you’ve got these expected cruise things, and then there’s the touches that makes Royal, Royal.
Next is ship size. When you’re talking Oasis class ships you can’t really avoid this as they do dwarf other ships. Despite this the size is good relative to the number of passengers it carries. You do notice that there are a LOT of people upon embarkation and during the muster drill but it doesn’t really feel that overwhelming otherwise.
Kids clubs are arranged differently. Oceaneers is designed as an open area and kids 3-11 can roam around and basically do what they want. Depending on the kids in the club this can get chaotic.
Adventure Ocean takes that 3-11 group and divides them further into 3 smaller groups, with themed programs that they try to get kids to participate in. Depending on the kids in the club this can get chaotic.
Pools are an easy win for Harmony, EXCEPT when it comes to the adults area, since there is no pool in the Solarium. You’ve got 3 pools, a large kids splash area with prominent deck placement, and 3 water slides (2 traditional, 1 funnel/toilet bowl style)
Dining. I think this is a spot where “bringing Disney to a ship” is noticeable, as DCL’s wait staff seems to be consistently good. Royal is hit or miss - if you get good servers, you’ll know it. Ditto for bad ones. Food in the MDR is subjective, And it’ll vary from person to person. Buffets are about equivalent. Seating feels more open in Windjammer vs Cabanas, and I attribute that to Cabanas having to accommodate the cola machines. Cabanas seems to offer more sushi,WJ has curries and Southeast Asian offerings, if that makes any difference. Harmony also offers congee for breakfast, but ymmv on that.
Royal has a $7.95 charge for all room service save for continental breakfast. I never order room service, so I’ve no first-hand experience here. I love eating at Johnny Rockets for breakfast. Not so much for the food, but eating out on the empty Boardwalk is very relaxing.
Royal has more specialty restaurants, and they allow kids. Never been to Palo and Remy, and only went to Chops on Harmony. Which was pretty good. It’s not Ruth’s Chris, but it’s better than The Keg. I’ve been to Jamie’s Italian here in Toronto, and it’s pretty good Italian fare. I would rate it slightly above most of the chain brands, but from what I’ve heard it won’t match up to Palo.
Coffee. Harmony has drip coffee, DCL has something that resembles coffee.
I think I need to do a part two.