A futon is different from a sofa bed and a daybed, but each serves a dual purpose. A futon features a foldable frame with a mattress that acts as both seating and a sleeping space. A sofa bed resembles a normal sofa, but stashed underneath the cushions is a queen-sized mattress that you can pull out. A daybed is made to resemble a sofa, but with a twin mattress on top – no conversion is needed here, so it’s always ready for you to sleep on.