foam rubber vs gum elastic

foam rubber and gum elastic both are nouns.

Word	Noun	Adjective	Verb	Adverb
foam rubber	Yes	No	No	No
gum elastic	Yes	No	No	No

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

foam rubber: spongy rubber; made by introducing air bubbles before vulcanization and used for cushioning or upholstery
gum elastic: an elastic material obtained from the latex sap of trees (especially trees of the genera Hevea and Ficus) that can be vulcanized and finished into a variety of products

Other hypernyms of foam rubber include foam, caoutchouc, India rubber, natural rubber, rubber.

foam rubber (noun)	gum elastic (noun)
spongy rubber; made by introducing air bubbles before vulcanization and used for cushioning or upholstery	an elastic material obtained from the latex sap of trees (especially trees of the genera Hevea and Ficus) that can be vulcanized and finished into a variety of products