fetlock joint vs articulatio

fetlock joint and articulatio both are nouns.

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

As nouns, articulatio is a hypernym of fetlock joint; that is, articulatio is a word with a broader meaning than fetlock joint:

fetlock joint: the joint between the cannon bone and the pastern
articulatio: (anatomy) the point of connection between two bones or elements of a skeleton (especially if it allows motion)

Other hypernyms of fetlock joint include articulation, joint.

fetlock joint (noun)	articulatio (noun)
the joint between the cannon bone and the pastern	(anatomy) the point of connection between two bones or elements of a skeleton (especially if it allows motion)