rotary encoder vs shaft encoder

rotary encoder and shaft encoder both are nouns.

Word	Noun	Adjective	Verb	Adverb
rotary encoder	Yes	No	No	No
shaft encoder	Yes	No	No	No

As nouns, rotary encoder and shaft encoder are synonyms defined as:

rotary encoder and shaft encoder: an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital code.

rotary encoder (noun)	shaft encoder (noun)
an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital code.	an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital code.