granny knot vs granny

granny knot and granny both are nouns.

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

As nouns, granny knot and granny are synonyms defined as:

granny knot and granny: a reef knot crossed the wrong way and therefore insecure

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