wiper vs mechanical device

wiper and mechanical device both are nouns.

Word	Noun	Adjective	Verb	Adverb
wiper	Yes	No	No	No
mechanical device	Yes	No	No	No

As nouns, mechanical device is a hypernym of wiper; that is, mechanical device is a word with a broader meaning than wiper:

wiper: a mechanical device that cleans the windshield
mechanical device: mechanism consisting of a device that works on mechanical principles

wiper (noun)	mechanical device (noun)
a mechanical device that cleans the windshield	mechanism consisting of a device that works on mechanical principles
contact consisting of a conducting arm that rotates over a series of fixed contacts and comes to rest on an outlet
a worker who wipes