male genitals vs male genital organ

male genitals and male genital organ both are nouns.

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

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

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

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