Gel is a recent newcomer to the mattress space. It is being used as both a standalone layer and an infusion into foam. Gel benefits mattresses by retaining less heat than memory foam. Also, newer gels compete against memory foam by being more responsive and less toxic.
Gel is similar to foam because it is a polymer made by blending plastics and other chemicals.
Because of gel's heat diffusing properties, it is generally found in the top layer of the mattress under the cover.
Pros: Cooler sleeping surface vs memory foam. More responsive feel when not combined with foam.
Cons: Similar to foam, it is a synthetic blend of chemicals.
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:
Gel: 8.6/10
Pillow Top: 8.9/10
Comfort:
Gel: 8.7/10
Pillow Top: 9/10
Softness:
Gel: 8/10
Pillow Top: 9.4/10
Cooling:
Gel: 8.1/10
Pillow Top: 8.2/10
Hypoallergenic:
Gel: 8.1/10
Pillow Top: 8.5/10
Odor:
Gel: 8.1/10
Pillow Top: 8.2/10
General Support:
Gel: 8.1/10
Pillow Top: 8.2/10
Eco-Conscious:
Gel: 8/10
Pillow Top: 8.5/10
Price Value:
Gel: 9.2/10
Pillow Top: 8.2/10