sutural bone vs os

sutural bone and os both are nouns.

Word	Noun	Adjective	Verb	Adverb
sutural bone	Yes	No	No	No
os	Yes	No	No	No

As nouns, os is a hypernym of sutural bone; that is, os is a word with a broader meaning than sutural bone:

sutural bone: any of the tiny soft bones found in the sutures between cranial bones
os: rigid connective tissue that makes up the skeleton of vertebrates

Other hypernyms of sutural bone include bone.

sutural bone (noun)	os (noun)
any of the tiny soft bones found in the sutures between cranial bones	rigid connective tissue that makes up the skeleton of vertebrates
	a mouth or mouthlike opening