rounding vs rounding error

rounding and rounding error both are nouns.

Word	Noun	Adjective	Verb	Adverb
rounding	Yes	No	No	No
rounding error	Yes	No	No	No

As nouns, rounding and rounding error are synonyms defined as:

rounding and rounding error: (mathematics) a miscalculation that results from rounding off numbers to a convenient number of decimals

rounding (noun)	rounding error (noun)
(mathematics) a miscalculation that results from rounding off numbers to a convenient number of decimals	(mathematics) a miscalculation that results from rounding off numbers to a convenient number of decimals