Hi stockdog,
Post #6 here should help you compare them 
There is more about the different types and blends of latex in post #6 here. Latex is “differentiated” both by the manufacturing process (Dunlop or Talalay) and by the percentage of natural or synthetic rubber that is used to make it. The word “latex” covers anything that uses latex in any form (Dunlop or Talalay that is made from either natural rubber, synthetic rubber, or a blend of both).
The word “foam” is just a generic term that means a material that is made to have air bubbles inside it. It can refer to any version of the three main foam materials that are used in mattresses which are polyfoam, memory foam, or latex foam. Both mattresses use latex as the comfort layer and have a polyfoam support core so they are both latex/polyfoam hybrid mattresses although the specific type of polyfoam and latex that is used in both of them are different.
Phoenix