changer vs mechanical device

changer and mechanical device both are nouns.

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

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

changer: an automatic mechanical device on a record player that causes new records to be played without manual intervention
mechanical device: mechanism consisting of a device that works on mechanical principles

changer (noun)	mechanical device (noun)
an automatic mechanical device on a record player that causes new records to be played without manual intervention	mechanism consisting of a device that works on mechanical principles
a person who changes something