pubic bone vs pelvic girdle

pubic bone and pelvic girdle both are nouns.

Word	Noun	Adjective	Verb	Adverb
pubic bone	Yes	No	No	No
pelvic girdle	Yes	No	No	No

pubic bone (noun)	pelvic girdle (noun)
one of the three sections of the hipbone; together these two bones form the front of the pelvis	the structure of the vertebrate skeleton supporting the lower limbs in humans and the hind limbs or corresponding parts in other vertebrates