tea napkin vs napkin

tea napkin and napkin both are nouns.

Word	Noun	Adjective	Verb	Adverb
tea napkin	Yes	No	No	No
napkin	Yes	No	No	No

As nouns, napkin is a hypernym of tea napkin; that is, napkin is a word with a broader meaning than tea napkin:

tea napkin: a small napkin used when tea is served
napkin: a small piece of table linen that is used to wipe the mouth and to cover the lap in order to protect clothing

Other hypernyms of tea napkin include serviette, table napkin.

tea napkin (noun)	napkin (noun)
a small napkin used when tea is served	a small piece of table linen that is used to wipe the mouth and to cover the lap in order to protect clothing
	garment consisting of a folded cloth drawn up between the legs and fastened at the waist; worn by infants to catch excrement