malted milk vs milk shake

malted milk and milk shake both are nouns.

Word	Noun	Adjective	Verb	Adverb
malted milk	Yes	No	No	No
milk shake	Yes	No	No	No

As nouns, milk shake is a hypernym of malted milk; that is, milk shake is a word with a broader meaning than malted milk:

malted milk: a milkshake made with malt powder
milk shake: frothy drink of milk and flavoring and sometimes fruit or ice cream

Other hypernyms of malted milk include milkshake, shake.

malted milk (noun)	milk shake (noun)
powder made of dried milk and malted cereals	frothy drink of milk and flavoring and sometimes fruit or ice cream
a milkshake made with malt powder