coxa vs hip joint

coxa and hip joint both are nouns.

Word	Noun	Adjective	Verb	Adverb
coxa	Yes	No	No	No
hip joint	Yes	No	No	No

As nouns, coxa and hip joint are synonyms defined as:

coxa and hip joint: the ball-and-socket joint between the head of the femur and the acetabulum

Other synonyms of coxa include articulatio coxae, hip.

coxa (noun)	hip joint (noun)
the ball-and-socket joint between the head of the femur and the acetabulum	the ball-and-socket joint between the head of the femur and the acetabulum