This misconception has been around for sometime. Mats can be seen advertised or referred to as foam rubber which is contradictory.
The fact is Foam floor tiles are made from EVA (Ethylene-vinyl acetate) memory foam. This material is used in many products such as running shoes and sports equipment for example.
In contrast rubber tiles are made from virgin rubber (directly from trees or synthetically; SBR rubber is recycled from tyres or EPDM for flecked rubber.
In short, EVA memory foam is light and inexpensive, absorbs impact but hard sharp objects will dent and cut the mats. Whereas rubber is heavy, dense and more durable.
Suitability: Consider traffic and weight demands of your floor. EVA foam is suitable for break falls and light weights whereas rubber is best suited for heavy weight or cross fit.