donut fryer vs doughnut fryer

donut fryer and doughnut fryer both are nouns.

Word	Noun	Adjective	Verb	Adverb
donut fryer	Yes	No	No	No
doughnut fryer	Yes	No	No	No

As nouns, donut fryer and doughnut fryer are synonyms defined as:

donut fryer and doughnut fryer: a machine used to fry large quantities of doughnuts at once.

Other synonyms of donut fryer include donut machine, doughnut machine.

donut fryer (noun)	doughnut fryer (noun)
a machine used to fry large quantities of doughnuts at once.	a machine used to fry large quantities of doughnuts at once.