Merriam Webster defines the substances as:
Latex (noun): a milky usually white fluid that is produced by cells of various seed plants (as of the milkweed, spurge, and poppy families) and is the source of rubber.
Rubber (noun): an elastic substance that is obtained by coagulating the milky juice of any of various tropical plants (as of the genera Hevea and Ficus), is essentially a polymer of isoprene, and is prepared as sheets and then dried.
Our mattresses feature our GOLS organic certified Dunlop latex rubber foam. We collect the latex by tapping rubber trees, then we process the material, in a facility that we co-own, to create the natural, comfortable latex layer. We do not use polyurethane foams or synthetic latex.