rotary engine vs ICE

rotary engine and ICE both are nouns.

Word	Noun	Adjective	Verb	Adverb
rotary engine	Yes	No	No	No
ICE	Yes	No	No	No

As nouns, ICE is a hypernym of rotary engine; that is, ICE is a word with a broader meaning than rotary engine:

rotary engine: an internal-combustion engine in which power is transmitted directly to rotating components
ICE: a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbine

Other hypernyms of rotary engine include internal-combustion engine.

As nouns, ICE is a hypernym of rotary engine; that is, ICE is a word with a broader meaning than rotary engine:

rotary engine: an internal-combustion engine having cylinders arranged radially around a central crankcase
ICE: a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbine

Other hypernyms of rotary engine include internal-combustion engine.

rotary engine (noun)	ICE (noun)
an internal-combustion engine in which power is transmitted directly to rotating components	a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbine
an internal-combustion engine having cylinders arranged radially around a central crankcase