male genital organ vs male genitalia

male genital organ and male genitalia both are nouns.

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

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

Other synonyms of male genital organ include family jewels, male genitals.

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