brain sugar vs saccharose

brain sugar and saccharose both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain sugar	Yes	No	No	No
saccharose	Yes	No	No	No

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

brain sugar: a simple sugar found in lactose
saccharose: a complex carbohydrate found in many plants and used as a sweetening agent

Other hypernyms of brain sugar include sucrose.

brain sugar (noun)	saccharose (noun)
a simple sugar found in lactose	a complex carbohydrate found in many plants and used as a sweetening agent