reef knot vs granny

reef knot and granny both are nouns.

Word	Noun	Adjective	Verb	Adverb
reef knot	Yes	No	No	No
granny	Yes	No	No	No

As nouns, granny is a hyponym of reef knot; that is, granny is a word with a more specific, narrower meaning than reef knot:

Other hyponyms of reef knot include granny knot.

reef knot (noun)	granny (noun)
a square knot used in a reef line	a reef knot crossed the wrong way and therefore insecure
	the mother of your father or mother
	an old woman