chest vs pix chest

chest and pix chest both are nouns.

Word	Noun	Adjective	Verb	Adverb
chest	Yes	No	No	No
pix chest	Yes	No	No	No

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

chest (noun)	pix chest (noun)
box with a lid; used for storage; usually large and sturdy	a chest in which coins from the mint are held to await assay
furniture with drawers for keeping clothes
the part of the human torso between the neck and the diaphragm or the corresponding part in other vertebrates
the front of the trunk from the neck to the abdomen