radial engine vs rotary engine

radial engine and rotary engine both are nouns.

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

As nouns, radial engine and rotary engine are synonyms defined as:

radial engine and rotary engine: an internal-combustion engine having cylinders arranged radially around a central crankcase

radial engine (noun)	rotary engine (noun)
an internal-combustion engine having cylinders arranged radially around a central crankcase	an internal-combustion engine in which power is transmitted directly to rotating components
	an internal-combustion engine having cylinders arranged radially around a central crankcase