In terms of locations detailed, they will probably be about the same, one with a chapter detailing the Radiant Citadel, and the other will have a chapter detailing the Rock of Bral.
But Spelljammer is a book about traveling between worlds, not describing the contents of the entire multiverse. In the 5e sense "setting" means "type of story" not rattling off a long list of locations.
Do not expect the locations in the Radiant Citadel adventures to be detailed. Candlekeep Mysteries goes to places like Tashluta and Anauroch, but it only has very cursory information about those locations (and no map).