alveolus vs air cell

alveolus and air cell both are nouns.

Word	Noun	Adjective	Verb	Adverb
alveolus	Yes	No	No	No
air cell	Yes	No	No	No

As nouns, alveolus and air cell are synonyms defined as:

alveolus and air cell: a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways

Other synonyms of alveolus include air sac.

alveolus (noun)	air cell (noun)
a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways	a tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air passageways
a bony socket in the alveolar ridge that holds a tooth