grinning vs grin

grinning and grin both are nouns.

Word	Noun	Adjective	Verb	Adverb
grinning	Yes	No	No	No
grin	Yes	No	Yes	No

As nouns, grinning and grin are synonyms defined as:

grinning and grin: a facial expression characterized by turning up the corners of the mouth; usually shows pleasure or amusement

Other synonyms of grinning include smile, smiling.

grinning (noun)	grin (noun)
a facial expression characterized by turning up the corners of the mouth; usually shows pleasure or amusement	a facial expression characterized by turning up the corners of the mouth; usually shows pleasure or amusement

grinning (verb)	grin (verb)
	to draw back the lips and reveal the teeth, in a smile, grimace, or snarl