testis vs sex gland

testis and sex gland both are nouns.

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

As nouns, sex gland is a hypernym of testis; that is, sex gland is a word with a broader meaning than testis:

testis: one of the two male reproductive glands that produce spermatozoa and secrete androgens
sex gland: a gland in which gametes (sex cells) are produced

Other hypernyms of testis include gonad, male reproductive gland.

testis (noun)	sex gland (noun)
one of the two male reproductive glands that produce spermatozoa and secrete androgens	a gland in which gametes (sex cells) are produced