safety vs device

safety and device both are nouns.

Word	Noun	Adjective	Verb	Adverb
safety	Yes	No	No	No
device	Yes	No	No	No

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

safety (noun)	device (noun)
(baseball) the successful act of striking a baseball in such a way that the batter reaches base safely	any clever maneuver
a score in American football; a player is tackled behind his own goal line	an instrumentality invented for a particular purpose
a device designed to prevent injury or accidents	an emblematic design (especially in heraldry)
contraceptive device consisting of a sheath of thin rubber or latex that is worn over the penis during intercourse	any ornamental pattern or design (as in embroidery)
a safe place	something in an artistic work designed to achieve a particular effect
the state of being certain that adverse effects will not be caused by some agent under defined conditions