male genitalia vs male genital organ

male genitalia and male genital organ both are nouns.

Word	Noun	Adjective	Verb	Adverb
male genitalia	Yes	No	No	No
male genital organ	Yes	No	No	No

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

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

male genitalia (noun)	male genital organ (noun)
external male sex organs	external male sex organs