circumference vs borderline

circumference and borderline both are nouns.

Word	Noun	Adjective	Verb	Adverb
circumference	Yes	No	No	No
borderline	Yes	Yes	No	No

As nouns, borderline is a hypernym of circumference; that is, borderline is a word with a broader meaning than circumference:

Other hypernyms of circumference include border, boundary line, delimitation, mete.

circumference (noun)	borderline (noun)
the size of something as given by the distance around it	a line that indicates a boundary
the length of the closed curve of a circle
the boundary line encompassing an area or object

circumference (adjective)	borderline (adjective)
	of questionable or minimal quality