pallium vs archipallium

pallium and archipallium both are nouns.

Word	Noun	Adjective	Verb	Adverb
pallium	Yes	No	No	No
archipallium	Yes	No	No	No

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

pallium: the layer of unmyelinated neurons (the grey matter) forming the cortex of the cerebrum
archipallium: the olfactory cortex of the cerebrum

Other hyponyms of pallium include neocortex, neopallium, paleocortex.

pallium (noun)	archipallium (noun)
cloak or mantle worn by men in ancient Rome	the olfactory cortex of the cerebrum
(Roman Catholic Church) vestment consisting of a band encircling the shoulders with two lappets hanging in front and back
(zoology) a protective layer of epidermis in mollusks or brachiopods that secretes a substance forming the shell
the layer of unmyelinated neurons (the grey matter) forming the cortex of the cerebrum