Al vs ammonia alum

Al and ammonia alum both are nouns.

Word	Noun	Adjective	Verb	Adverb
Al	Yes	No	No	No
ammonia alum	Yes	No	No	No

As nouns, ammonia alum is a hyponym of Al; that is, ammonia alum is a word with a more specific, narrower meaning than Al:

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

Other hyponyms of Al include alum, potash alum, potassium alum, alum, ammonium alum.

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