A mattress in a box is no different from a mattress that you buy in a store. The only way it differs is that it is compressed and rolled up into a box for shipping. Once you unbox a mattress and allow it time to reach its full shape, it will offer the same performance features that you would find in a similar mattress purchased from a brick-and-mortar store. Mattresses in a box also tend to be less expensive than store-bought beds, since companies do not need to pay for as many overhead costs.