lower jawbone vs lower jaw

lower jawbone and lower jaw both are nouns.

Word	Noun	Adjective	Verb	Adverb
lower jawbone	Yes	No	No	No
lower jaw	Yes	No	No	No

As nouns, lower jawbone and lower jaw are synonyms defined as:

lower jawbone and lower jaw: the jaw in vertebrates that is hinged to open the mouth

Other synonyms of lower jawbone include jawbone, jowl, mandible, mandibula, mandibular bone, submaxilla.

lower jawbone (noun)	lower jaw (noun)
the jaw in vertebrates that is hinged to open the mouth	the jaw in vertebrates that is hinged to open the mouth