donut fryer vs deep fat fryer

donut fryer and deep fat fryer both are nouns.

Word	Noun	Adjective	Verb	Adverb
donut fryer	Yes	No	No	No
deep fat fryer	Yes	No	No	No

As nouns, deep fat fryer is a hypernym of donut fryer; that is, deep fat fryer is a word with a broader meaning than donut fryer:

donut fryer: a machine used to fry large quantities of doughnuts at once.
deep fat fryer: A kitchen appliance for deep frying; its size depends on intended use.

Other hypernyms of donut fryer include machine, deep fryer, frier, fryer, fryolator.

donut fryer (noun)	deep fat fryer (noun)
a machine used to fry large quantities of doughnuts at once.	A kitchen appliance for deep frying; its size depends on intended use.