kneepan vs sesamoid bone

kneepan and sesamoid bone both are nouns.

Word	Noun	Adjective	Verb	Adverb
kneepan	Yes	No	No	No
sesamoid bone	Yes	No	No	No

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

kneepan: a small flat triangular bone in front of the knee that protects the knee joint
sesamoid bone: any of several small round bones formed in a tendon where it passes over a joint

Other hypernyms of kneepan include os sesamoideum, sesamoid.

kneepan (noun)	sesamoid bone (noun)
a small flat triangular bone in front of the knee that protects the knee joint	any of several small round bones formed in a tendon where it passes over a joint