genu vs ginglymus

genu and ginglymus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genu	Yes	No	No	No
ginglymus	Yes	No	No	No

As nouns, ginglymus is a hypernym of genu; that is, ginglymus is a word with a broader meaning than genu:

genu: hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella
ginglymus: a freely moving joint in which the bones are so articulated as to allow extensive movement in one plane

Other hypernyms of genu include ginglymoid joint, hinge joint.

genu (noun)	ginglymus (noun)
hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella	a freely moving joint in which the bones are so articulated as to allow extensive movement in one plane