adjacent vs neighbouring

adjacent and neighbouring both are adjectives.

Word	Noun	Adjective	Verb	Adverb
adjacent	No	Yes	No	No
neighbouring	No	Yes	No	No

As adjectives, adjacent and neighbouring are synonyms defined as:

adjacent and neighbouring: having a common boundary or edge; abutting; touching

Other synonyms of adjacent include conterminous, contiguous, neighboring.

adjacent (adjective)	neighbouring (adjective)
nearest in space or position; immediately adjoining without intervening space	having a common boundary or edge; abutting; touching
having a common boundary or edge; abutting; touching
near or close to but not necessarily touching