Spectrum is unique in that it was designed for the Chinese market with a dedicated suite area on decks 15 and 16. The Sky Junior Suites are located in this area and have full suite benefits, while the other (Sea) Junior Suites are located elsewhere and do not have access. The rooms themselves are the same size and layout. There are also Sky Balcony cabins that get access, but are otherwise normal balcony rooms. I'm not sure what changes they have made to dining arrangements since moving to Singapore, but originally only the "Golden" (Sky/Star class) cabins had access to the suite restaurant within the dedicated area, while "Silver" (Sea class) cabins dined in the area that is usually Solarium Bistro.
Odyssey does not have the dedicated suite area and only has Sea class Junior Suites, with the suite lounge and Coastal Kitchen in the same areas as the other Quantum class ships. However, they are bringing back the dedicated suite area and Sky Junior Suite concept with Icon.