delimitation vs boundary line

delimitation and boundary line both are nouns.

Word	Noun	Adjective	Verb	Adverb
delimitation	Yes	No	No	No
boundary line	Yes	No	No	No

As nouns, delimitation and boundary line are synonyms defined as:

Other synonyms of delimitation include border, borderline, mete.

delimitation (noun)	boundary line (noun)
a line that indicates a boundary	a line that indicates a boundary