communion table vs altar

communion table and altar both are nouns.

Word	Noun	Adjective	Verb	Adverb
communion table	Yes	No	No	No
altar	Yes	No	No	No

As nouns, communion table and altar are synonyms defined as:

communion table and altar: the table in Christian churches where communion is given

Other synonyms of communion table include Lord's table.

communion table (noun)	altar (noun)
the table in Christian churches where communion is given	a raised structure on which gifts or sacrifices to a god are made
	the table in Christian churches where communion is given