Not long ago there were far fewer "comfort levels" when it came to mattresses. One brand felt a certain way; another brand felt a different way. Today most recognized brands offer a variety of feels that change with the amount of padding put on top of the mattress core. The firm bed is the most basic of these. When a mattress is called "firm," it usually means there is minimal padding in the top of the mattress and the material is stitched very tightly to prevent the sleeper from sinking into the bed. Such a mattress offers excellent support, but does not contour to the body very much. Those who sleep on their backs often prefer a firm mattress.
For those who are looking for similar firmness to the harder beds, but sleep in a way that makes the firm style apply too much pressure to their bodies when they lie down, the plush is often the answer. Plush stitching is sewn more loosely, and some brands add a bit more foam cushioning under the quilt -- from one to four inches worth of foam. This is a popular middle ground for many consumers, especially couples who disagree about how soft the bed should be. Typically within the same line of products, the plush version of a bed is otherwise identical in construction to the firm model.
Some people prefer the feeling often described as "sleeping on a cloud." Pillowtop mattresses were developed with these shoppers in mind. The pillowtop is nearly identical to its plush counterpart, only it has an additional thick pillow-like feather-bed layer sewn to the top of the mattress to add more softness to the feel. It is generally the softest of all the styles of beds. Although there is market for consumers who look specifically for pillowtop designs, they are not as popular as they once were. They are too soft for many people. Moreover, a new design in modern bedding has made the pillowtop less available as the box top or "Eurotop" replaces it.
Eurotop mattresses are the latest improvement to the pillowtop design. Instead of a separate pillow-like attachment sewn to the top of the mattress, the Eurotop actually builds an additional cushion straight up from the edges of the original mattress, making it all one continuous piece. Many Eurotops also utilize more foam options like visco-elastic "memory" foam or latex in the tops to give them a distinctive feel not available in other styles. The types of foam used can dictate the amount of softness in a Eurotop, making a fairly firm feeling mattress or one that is so soft it nearly swallows up the sleeper.