sex gland vs ovary

sex gland and ovary both are nouns.

Word	Noun	Adjective	Verb	Adverb
sex gland	Yes	No	No	No
ovary	Yes	No	No	No

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

sex gland: a gland in which gametes (sex cells) are produced
ovary: (vertebrates) one of usually two organs that produce ova and secrete estrogen and progesterone

Other hyponyms of sex gland include ovotestis, ball, ballock, bollock, egg, nut, orchis, testicle, testis.

sex gland (noun)	ovary (noun)
a gland in which gametes (sex cells) are produced	(vertebrates) one of usually two organs that produce ova and secrete estrogen and progesterone
	the organ that bears the ovules of a flower