curler vs mechanical device

curler and mechanical device both are nouns.

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

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

curler: a mechanical device consisting of a cylindrical tube around which the hair is wound to curl it
mechanical device: mechanism consisting of a device that works on mechanical principles

curler (noun)	mechanical device (noun)
a mechanical device consisting of a cylindrical tube around which the hair is wound to curl it	mechanism consisting of a device that works on mechanical principles