state boundary vs border

state boundary and border both are nouns.

Word	Noun	Adjective	Verb	Adverb
state boundary	Yes	No	No	No
border	Yes	No	Yes	No

As nouns, border is a hypernym of state boundary; that is, border is a word with a broader meaning than state boundary:

Other hypernyms of state boundary include borderline, boundary line, delimitation, mete.

state boundary (noun)	border (noun)
the boundary between two states	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

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