vocal organ vs organ of speech

vocal organ and organ of speech both are nouns.

Word	Noun	Adjective	Verb	Adverb
vocal organ	Yes	No	No	No
organ of speech	Yes	No	No	No

As nouns, vocal organ and organ of speech are synonyms defined as:

vocal organ and organ of speech: any of the organs involved in speech production

Other synonyms of vocal organ include speech organ.

vocal organ (noun)	organ of speech (noun)
any of the organs involved in speech production	any of the organs involved in speech production