simple sugar vs hexose

simple sugar and hexose both are nouns.

Word	Noun	Adjective	Verb	Adverb
simple sugar	Yes	No	No	No
hexose	Yes	No	No	No

As nouns, hexose is a hyponym of simple sugar; that is, hexose is a word with a more specific, narrower meaning than simple sugar:

simple sugar: a sugar (like sucrose or fructose) that does not hydrolyse to give other sugars; the simplest group of carbohydrates
hexose: a monosaccharide that contains six carbon atoms per molecule

Other hyponyms of simple sugar include triose, tetrose, pentose, aldose, ketose, heptose.

simple sugar (noun)	hexose (noun)
a sugar (like sucrose or fructose) that does not hydrolyse to give other sugars; the simplest group of carbohydrates	a monosaccharide that contains six carbon atoms per molecule