sugar loaf vs refined sugar

sugar loaf and refined sugar both are nouns.

Word	Noun	Adjective	Verb	Adverb
sugar loaf	Yes	No	No	No
refined sugar	Yes	No	No	No

As nouns, refined sugar is a hypernym of sugar loaf; that is, refined sugar is a word with a broader meaning than sugar loaf:

sugar loaf: a large conical loaf of concentrated refined sugar
refined sugar: a white crystalline carbohydrate used as a sweetener and preservative

Other hypernyms of sugar loaf include loaf, sugar.

sugar loaf (noun)	refined sugar (noun)
a large conical loaf of concentrated refined sugar	a white crystalline carbohydrate used as a sweetener and preservative