Xe vs inert gas

Xe and inert gas both are nouns.

Word	Noun	Adjective	Verb	Adverb
Xe	Yes	No	No	No
inert gas	Yes	No	No	No

As nouns, inert gas is a hypernym of Xe; that is, inert gas is a word with a broader meaning than Xe:

Xe: a colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amounts
inert gas: any of the chemically inert gaseous elements of the helium group in the periodic table

Other hypernyms of Xe include argonon, noble gas.

Xe (noun)	inert gas (noun)
a colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amounts	any of the chemically inert gaseous elements of the helium group in the periodic table