napkin vs serviette

napkin and serviette both are nouns.

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

As nouns, napkin and serviette are synonyms defined as:

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

Other synonyms of napkin include table napkin.

napkin (noun)	serviette (noun)
a small piece of table linen that is used to wipe the mouth and to cover the lap in order to protect clothing	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