You would be correct if you called a latex mattress a “rubber mattress”. The material to make a natural latex mattress comes from a rubber tree. Other beds, such as those with gel or memory foam, contain chemicals, so shoppers interested in a natural mattress are often attracted to the latex option.
Not all options in this category qualify as natural latex mattresses. Some latex beds have synthetic latex, which is still a type of rubber, but it is not from rubber trees. In other instances, a latex mattress could have a mixture of natural and synthetic materials.
There is some controversy about synthetic latex. Most people consider it chemical-free, but it is not as durable as a natural latex mattress, and it may or may not offer the same level of support.