pilar cyst vs chalazion

pilar cyst and chalazion both are nouns.

Word	Noun	Adjective	Verb	Adverb
pilar cyst	Yes	No	No	No
chalazion	Yes	No	No	No

As nouns, chalazion is a hyponym of pilar cyst; that is, chalazion is a word with a more specific, narrower meaning than pilar cyst:

pilar cyst: a common cyst of the skin; filled with fatty matter (sebum) that is secreted by a sebaceous gland that has been blocked
chalazion: a small sebaceous cyst of the eyelid resulting when a Meibomian gland is blocked

Other hyponyms of pilar cyst include Meibomian cyst.

pilar cyst (noun)	chalazion (noun)
a common cyst of the skin; filled with fatty matter (sebum) that is secreted by a sebaceous gland that has been blocked	a small sebaceous cyst of the eyelid resulting when a Meibomian gland is blocked