lactose vs milk sugar

lactose and milk sugar both are nouns.

Word	Noun	Adjective	Verb	Adverb
lactose	Yes	No	No	No
milk sugar	Yes	No	No	No

As nouns, lactose and milk sugar are synonyms defined as:

lactose and milk sugar: a sugar comprising one glucose molecule linked to a galactose molecule; occurs only in milk

lactose (noun)	milk sugar (noun)
a sugar comprising one glucose molecule linked to a galactose molecule; occurs only in milk	a sugar comprising one glucose molecule linked to a galactose molecule; occurs only in milk