language unit vs component part

language unit and component part both are nouns.

Word	Noun	Adjective	Verb	Adverb
language unit	Yes	No	No	No
component part	Yes	No	No	No

As nouns, component part is a hypernym of language unit; that is, component part is a word with a broader meaning than language unit:

language unit: one of the natural units into which linguistic messages can be analyzed
component part: something determined in relation to something that includes it

Other hypernyms of language unit include component, constituent, part, portion.

language unit (noun)	component part (noun)
one of the natural units into which linguistic messages can be analyzed	something determined in relation to something that includes it