labial palpus vs mouthpart

labial palpus and mouthpart both are nouns.

Word	Noun	Adjective	Verb	Adverb
labial palpus	Yes	No	No	No
mouthpart	Yes	No	No	No

As nouns, mouthpart is a hypernym of labial palpus; that is, mouthpart is a word with a broader meaning than labial palpus:

labial palpus: A labial palpus is either of the jointed appendages on the front of the mentum of an insect.
mouthpart: any part of the mouth of an insect or other arthropod especially one adapted to a specific way of feeding

Other hypernyms of labial palpus include appendage, outgrowth, process.

labial palpus (noun)	mouthpart (noun)
A labial palpus is either of the jointed appendages on the front of the mentum of an insect.	any part of the mouth of an insect or other arthropod especially one adapted to a specific way of feeding