Crib mattresses have a few differences from toddler mattresses, but they are pretty much the same. Most importantly, toddler mattresses are the same size as crib mattresses. u003cbr/u003eu003cbr/u003eSome of the best non-toxic crib mattresses feature a dual system specifically designed for toddlers and infants. These dual-sided mattresses offer a firm side, the infant side, and a softer side, the toddler side.