Hi Diane,

Big differences between the two mattress.

1. Serta makes their mattresses with a continuous coil base. The problem inherent with that design is you will feel partner movement and added pressure from the coils as they are all attached. An all latex mattress usually relies on a latex foam base, which will not transfer motion like the continuous coil. Also, the foam base will not push your weight back towards your body like the coils, which is better for pressure relief and allows for better blood flow, which translates to longer bouts of deeper sleep.
2. The Serta uses visco-elastic foam, which traditionally uses blowing agents and other chemical reactives to create the foam from a blend of petroleum-based chemicals. These chemicals then off-gas in the form of a toxic VOC, volatile organic compound, and enter your body through the lungs. The natural latex mattress does not have any toxic VOC as the materials are derived from natural substances.
3. The natural mattress will traditionally use organic or natural wool to pass the fire test, while Serta traditionally uses a chemically treated sock around the foam in their mattress to pass the same test. These chemicals also will emit a toxic VOC, a chemical smell, which will enter your body through the lungs.
4. The Serta mattress will last maybe 5-7 years, while the natural latex mattress can last upwards of 15 - 20 years. It has to do with the low quality, low density foam in the Serta combined with the added upward pressure of the coils and your body weight pushing down on the low density foam, effectively wearing out the top from both sides. Latex is rubber, and a good quality latex can last a very long time.

Hope this helps!