sesamoid vs kneepan

sesamoid and kneepan both are nouns.

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

As nouns, kneepan is a hyponym of sesamoid; that is, kneepan is a word with a more specific, narrower meaning than sesamoid:

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

Other hyponyms of sesamoid include kneecap, patella.

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