As adjectives the difference between adjacent and attached
is that
adjacent is lying next to, close, or contiguous; neighboring; bordering on while
attached is in a romantic or sexual relationship.
As a noun adjacent
is something that lies next to something else, especially the side of a right triangle that is neither the hypotenuse nor the opposite.
As a preposition adjacent
is (us) next to; adjacent to; beside.
As a verb attached is
(
attach).