Adjoining Room -
While people often use "adjoining" and "connecting" interchangeably, there is a technical difference in the hospitality industry:
: Rooms that feature an internal door, allowing guests to move between them without entering the hallway. Adjoining room meaning - BCD Travel adjoining room
An refers to two hotel guest rooms located next to each other that share a common wall. adjoining room
: Rooms located side-by-side or very close to each other (across a hall) that share a wall but do not necessarily have an interior door between them. Guests must use the public hallway to move between rooms. adjoining room