adjacent / adjoining
Near versus sharing a boundary.
Adjacent means next to or very near; the things may or may not touch. Adjoining means joined: they share a wall, edge, or border. Rooms across a hall can be adjacent. Rooms that share a door are adjoining. When the distinction matters, keep it. When it does not, adjacent will usually do.
Examples
UseThe hotel is adjacent to the station.
UseThey booked adjoining rooms.
AvoidThey booked adjacent rooms. (Fine if you only mean nearby; not if you mean a connecting door.)