adjoin vs border

adjoin is not a noun while border is a noun.

Word	Noun	Adjective	Verb	Adverb
adjoin	No	No	Yes	No
border	Yes	No	Yes	No

As verbs, adjoin and border are synonyms defined as:

Other synonyms of adjoin include abut, butt, butt against, butt on, edge, march.

As verbs, border is a hyponym of adjoin; that is, border is a word with a more specific, narrower meaning than adjoin:

adjoin (noun)	border (noun)
	a strip forming the outer edge of something
	a decorative recessed or relieved surface on an edge
	a line that indicates a boundary
	the boundary of a surface
	the boundary line or the area immediately inside the boundary

adjoin (verb)	border (verb)
attach or add	lie adjacent to another or share a boundary
lie adjacent to another or share a boundary	extend on all sides of simultaneously; encircle
be in direct physical contact with; make contact	enclose in or as if in a frame
	provide with a border or edge
	form the boundary of; be contiguous to