smile vs grin

smile and grin both are nouns.

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

As nouns, smile and grin are synonyms defined as:

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

Other synonyms of smile include grinning, smiling.

As verbs, grin is a hyponym of smile; that is, grin is a word with a more specific, narrower meaning than smile:

smile: change one's facial expression by spreading the lips, often to signal pleasure
grin: to draw back the lips and reveal the teeth, in a smile, grimace, or snarl

Other hyponyms of smile include dimple, beam, simper, smirk, sneer.

smile (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

smile (verb)	grin (verb)
change one's facial expression by spreading the lips, often to signal pleasure	to draw back the lips and reveal the teeth, in a smile, grimace, or snarl
express with a smile