Egg crate foam can be any type of foam where one side has an 'egg crate' shape. The purpose of this kind of foam is two-fold. It tends to be more responsive and distributes weight better than a thick layer of foam, and also it has cooling advantages because of the air flow that it provides.
Egg crate foam can be either memory foam or reflex foam, which are both blends of polyurethane foams and could be prone to off-gassing and odor.
The egg crate foam is generally found in the top comfort layers of the mattress, though they could be used in the base layer as well.
Pros: More response and more airflow than flat foam layers.
Cons: Comfort is entirely dependent on the quality of foam -- lower quality foams can be uncomfortable and break down faster.
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.
Overall Score:
Egg Crate Foam: 9.2/10
Gel: 8.6/10
Comfort:
Egg Crate Foam: 9.2/10
Gel: 8.7/10
Softness:
Egg Crate Foam: 9.4/10
Gel: 8/10
Cooling:
Egg Crate Foam: 8.9/10
Gel: 8.1/10
Hypoallergenic:
Egg Crate Foam: 8.9/10
Gel: 8.1/10
Odor:
Egg Crate Foam: 8.6/10
Gel: 8.9/10
General Support:
Egg Crate Foam: 9/10
Gel: 9.5/10
Eco-Conscious:
Egg Crate Foam: 8.9/10
Gel: 8.1/10
Price Value:
Egg Crate Foam: 9.2/10
Gel: 9.2/10