rubber band vs elastic device

rubber band and elastic device both are nouns.

Word	Noun	Adjective	Verb	Adverb
rubber band	Yes	No	No	No
elastic device	Yes	No	No	No

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

rubber band: a narrow band of elastic rubber used to hold things (such as papers) together
elastic device: any flexible device that will return to its original shape when stretched

Other hypernyms of rubber band include band.

rubber band (noun)	elastic device (noun)
a narrow band of elastic rubber used to hold things (such as papers) together	any flexible device that will return to its original shape when stretched