ammonium alum vs aluminium

ammonium alum and aluminium both are nouns.

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

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

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

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

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