fetlock joint vs fetlock

fetlock joint and fetlock both are nouns.

Word	Noun	Adjective	Verb	Adverb
fetlock joint	Yes	No	No	No
fetlock	Yes	No	No	No

As nouns, fetlock joint and fetlock are synonyms defined as:

fetlock joint and fetlock: the joint between the cannon bone and the pastern

fetlock joint (noun)	fetlock (noun)
the joint between the cannon bone and the pastern	projection behind and above a horse's hoof
	the joint between the cannon bone and the pastern