The Kempinski Aqaba is a superb property. Wonderful architecture (the public areas and the pool are gorgeous), excellent hard product and great service. The food is very good too from my limited experience of an in-room dinner and a breakfast. The breakfast buffet had an astonishing array of tempting items, beautifully presented on individual plates.
The Kempinski Ishtar is more of a typical resort. Although it too has lavish architecture and grand public spaces it didn't feel like the same league as the one in Aqaba. A solid 5* property but lacking the elusive luxury edge. The spa, however is astounding - huge and spacious with amazing facilities including its own private pool and lawns.