reredos vs altarpiece

reredos and altarpiece both are nouns.

Word	Noun	Adjective	Verb	Adverb
reredos	Yes	No	No	No
altarpiece	Yes	No	No	No

As nouns, reredos and altarpiece are synonyms defined as:

reredos and altarpiece: a painted or carved screen placed above and behind an altar or communion table

reredos (noun)	altarpiece (noun)
a painted or carved screen placed above and behind an altar or communion table	a painted or carved screen placed above and behind an altar or communion table