adjoin vs edge

adjoin is not a noun while edge is a noun.

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

As verbs, adjoin and edge are synonyms defined as:

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

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

adjoin (noun)	edge (noun)
	a sharp side formed by the intersection of two surfaces of an object
	the outside limit of an object or area or surface; a place farthest away from the center of something
	a slight competitive advantage
	the attribute of urgency in tone of voice
	the boundary of a surface
	a line determining the limits of an area

adjoin (verb)	edge (verb)
attach or add	lie adjacent to another or share a boundary
lie adjacent to another or share a boundary	provide with an edge
be in direct physical contact with; make contact	advance slowly, as if by inches
	provide with a border or edge