coronal suture vs fibrous joint

coronal suture and fibrous joint both are nouns.

Word	Noun	Adjective	Verb	Adverb
coronal suture	Yes	No	No	No
fibrous joint	Yes	No	No	No

As nouns, fibrous joint is a hypernym of coronal suture; that is, fibrous joint is a word with a broader meaning than coronal suture:

coronal suture: the suture between the parietal and frontal bones of the skull
fibrous joint: an immovable joint (especially between the bones of the skull)

Other hypernyms of coronal suture include sutura, suture.

coronal suture (noun)	fibrous joint (noun)
the suture between the parietal and frontal bones of the skull	an immovable joint (especially between the bones of the skull)