alveolar arch vs appendage

alveolar arch and appendage both are nouns.

Word	Noun	Adjective	Verb	Adverb
alveolar arch	Yes	No	No	No
appendage	Yes	No	No	No

As nouns, appendage is a hypernym of alveolar arch; that is, appendage is a word with a broader meaning than alveolar arch:

alveolar arch: the part of the upper or lower jawbones in which the teeth are set
appendage: a natural prolongation or projection from a part of an organism either animal or plant

Other hypernyms of alveolar arch include outgrowth, process.

alveolar arch (noun)	appendage (noun)
the part of the upper or lower jawbones in which the teeth are set	a part that is joined to something larger
	an external body part that projects from the body
	a natural prolongation or projection from a part of an organism either animal or plant