The difference between roll mattresses and conventional mattresses is really only the format in which they are purchased. Roll mattresses are, as the name suggests, rolled mattresses. This means that they take up much less space and are easier to transport. So you don't need a van, but can easily store the mattress in the boot of your car. This has the huge advantage that when you go to a mattress outlet or discount store to try out different mattresses, you can just pack them up and take them home.