shaft encoder vs rotary encoder

shaft encoder and rotary encoder both are nouns.

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

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

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

shaft encoder (noun)	rotary 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.