narrow margin vs margin

narrow margin and margin both are nouns.

Word	Noun	Adjective	Verb	Adverb
narrow margin	Yes	No	No	No
margin	Yes	No	No	No

As nouns, margin is a hypernym of narrow margin; that is, margin is a word with a broader meaning than narrow margin:

narrow margin (noun)	margin (noun)
a small margin	an amount beyond the minimum necessary
	a permissible difference; allowing some freedom to move within limits
	the blank space that surrounds the text on a page
	the amount of collateral a customer deposits with a broker when borrowing from the broker to buy securities
	(finance) the net sales minus the cost of goods and services sold
	the boundary line or the area immediately inside the boundary