potassium alum vs potash alum

potassium alum and potash alum both are nouns.

Word	Noun	Adjective	Verb	Adverb
potassium alum	Yes	No	No	No
potash alum	Yes	No	No	No

As nouns, potassium alum and potash alum are synonyms defined as:

potassium alum and potash alum: a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum

Other synonyms of potassium alum include alum.

potassium alum (noun)	potash alum (noun)
a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum	a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum