family jewels vs male genital organ

family jewels and male genital organ both are nouns.

Word	Noun	Adjective	Verb	Adverb
family jewels	Yes	No	No	No
male genital organ	Yes	No	No	No

As nouns, family jewels and male genital organ are synonyms defined as:

Other synonyms of family jewels include male genitalia, male genitals.

family jewels (noun)	male genital organ (noun)
external male sex organs	external male sex organs