sex cell vs gamete

sex cell and gamete both are nouns.

Word	Noun	Adjective	Verb	Adverb
sex cell	Yes	No	No	No
gamete	Yes	No	No	No

As nouns, gamete is a hyponym of sex cell; that is, gamete is a word with a more specific, narrower meaning than sex cell:

sex cell: a spermatozoon or an ovum; a cell responsible for transmitting DNA to the next generation
gamete: a mature sexual reproductive cell having a single set of unpaired chromosomes

sex cell (noun)	gamete (noun)
a spermatozoon or an ovum; a cell responsible for transmitting DNA to the next generation	a mature sexual reproductive cell having a single set of unpaired chromosomes