It's the acessible rooms, so only cabins below or above both decks 6 and 8, no theatre or kids clubs i dont think.
My husband would have to use the lifts most of the time anyway, as he can't walk very easily (often using his stick or mobility scooter).
We did deck 8 last time on the dream, but were just thinking if saving the money would be better, if there wasn't any major reasons not to go for deck 6.