potassium alum vs aluminium

potassium alum and aluminium both are nouns.

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

As nouns, aluminium is a hypernym of potassium alum; that is, aluminium is a word with a broader meaning than potassium alum:

potassium alum: a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum
aluminium: a silvery ductile metallic element found primarily in bauxite

Other hypernyms of potassium alum include Al, aluminum, atomic number 13, double salt.

potassium alum (noun)	aluminium (noun)
a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum	a silvery ductile metallic element found primarily in bauxite