saltpeter vs niter

saltpeter and niter both are nouns.

Word	Noun	Adjective	Verb	Adverb
saltpeter	Yes	No	No	No
niter	Yes	No	No	No

As nouns, saltpeter and niter are synonyms defined as:

saltpeter and niter: (KNO3) used especially as a fertilizer and explosive

Other synonyms of saltpeter include nitre, potassium nitrate, saltpetre.

saltpeter (noun)	niter (noun)
(KNO3) used especially as a fertilizer and explosive	(KNO3) used especially as a fertilizer and explosive