What is the difference between memory foam and latex?

la·tex
noun
a milky fluid found in many plants, such as poppies and spurges, that exudes when the plant is cut and coagulates on exposure to the air. The latex of the rubber tree is the chief source of natural rubber.
a synthetic product resembling latex, consisting of a dispersion in water of polymer particles, used to make paints, coatings, and other products.
plural noun: latexes; plural noun: latices
a type of paint used for walls, consisting of pigment bound in synthetic latex that forms an emulsion with water.
noun: latex paint; plural noun: latex paints
~google.com

mem·o·ry foam
noun
a polyurethane material that is sensitive to pressure and temperature, used especially in mattresses, where it molds to the shape of an individual's body.
~google.com