male genital organ vs male genitals

male genital organ and male genitals both are nouns.

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

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

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

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