leg bone vs long bone

leg bone and long bone both are nouns.

Word	Noun	Adjective	Verb	Adverb
leg bone	Yes	No	No	No
long bone	Yes	No	No	No

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

leg bone: a bone of the leg
long bone: in limbs of vertebrate animals: a long cylindrical bone that contains marrow

Other hypernyms of leg bone include os longum.

leg bone (noun)	long bone (noun)
a bone of the leg	in limbs of vertebrate animals: a long cylindrical bone that contains marrow