A pillow top is a surface layer of soft material that is stitched and packed into the cover. This provides a soft as a cloud feel to the surface of the mattress.
There are multiple types of pillow tops, though the most popular recently is a memory foam pillow top. A memory foam pillow top has a thin layer of soft memory foam that is stitched into the cover. Though memory foam is a popular material for pillow tops, you can also find them with latex, cotton, cashmere, wool, or goose down/feathers.
Pillow top mattresses generally have spring support systems in the middle of the mattress, though there could be a pillow top on a memory foam mattress as well (it is just not very common).
Pros: A plush feel on the top of the mattress that pillows the body on top of the support layers.
Cons: The pillow top alone will not make a good bed -- the materials used in the pillow top and the rest of the mattress can sag or have issues if they are lower quality.
Overall Score: 8.9/10
General Support: 8.3/10
Price Value: 8.3/10
Pillow tops are made of a cover fabric (such as polyester, cotton, or a blend) and comfort material. The comfort material can either be packed if it is loose like cotton or goose down or it can be layered if it is a foam.
If you want a softer feel, then a pillow top is a good option -- though do your research as there are plenty of soft varieties of mattresses that don't have pillow tops and are excellent!