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.
Innerspring systems describe mattresses made with coil systems. Traditional innerspring mattresses were made with interconnected coils, providing structure to the bed. In recent years, some have used 'innerspring' to describe newer pocket spring systems that are independent and offer greater comfort.
In general, most use 'innerspring' to describe the traditional mattress styles and those that purchased a mattress in the 20th century are very used to these types of beds.
The interconnected spring systems offer a high amount of durability and support, but there are complaints of aggravated pressure points and discomfort despite comfort layers of foams on the surface.
Pros: Durable materials and traditional even feel.
Cons: Pressure point discomfort and motion transfer issues.