Platform Base.

A divan base with a solid top, can come with or without storage drawers.

View from inside a platform divan base.

Sprung Edge base.

A divan base with springs in the top, the springs will run right to the edge of the divan, hence the name. This gives a mattresses a more luxurious feel. But can also lengthen the life span of the mattress as it works as a "shock Absorber". Again can come with or without drawers.

Firm Edge Divan

A cross between the two, this type of base will be sprung in the middle but rigid around the edge. Usually found on a shallower divan base and on legs. A firmer edge can be helpful for those who have difficulty in getting out of bed.

Image to follow.

Open Coil

The basic open coil spring unit is at the heart of most basic mattress. It consists of lots of "Bonnel coil spring" tied with a helicoil wire top and bottom. Fillings are added on top of the spring unit for extra comfort. The differences in price of the Open Coil mattress are due to the quality of the cover, fillings and quantity of the fillings. Handles and vents on the mattress will also add to it's value.

A single Bonnel open coil spring

Continuous Spring

Similarly to the Open coil unit the continuous spring unit is tied top and bottom with a helicoil wire. However the springs are smaller and there are nearly twice as many as the Open Coil Spring. The helicoil wire runs North to South of the mattress instead of East to West this helps eliminates "roll together". Again fillings are put on top of the springs for extra comfort.
Also notice that the continuous spring is not made up of individual springs, but one continuous wire.

Silentnight™'s Miracoil Spring Unit.

Pocket Sprung

Much much smaller springs in their own little pockets hence the name, these types of springs work for more independently giving much more support and true no roll together. Pocket springs come in what's known as "Spring Count", this count is always the number of springs based on a 5ft (King Size) mattress. From as little as 600 through to 4,000-5,000 on the very top end products. Spring count has nothing to do with how firm or gentle a mattress will be, you can get gentle pockets and firmer pockets. As a general rule of thumb go for 1000 to 1600 springs.

Fillings come in many different types of materials, from Polyester pads, Silk, Wool, Horse hair, Foam, Memory Foam, Latex etc etc. The job of these fillings is to act as a comfort layer, so you can't feel the springs.

Memory Foam

Memory Foam is by far the largest change of all the bed fillings in recent years. Memory foam products come in 2 types of product, All Foam and Springs and Foam.

All foam Mattress Springs and foam mattress.

Very very few mattresses are ALL memory foam, in fact we know of only 1 on the market!
Memory foam needs a foundation, for own it's own it doesn't support anything. The all Foam mattresses will be memory foam on top of a denser foam. Springs and foam can be open coil or pocket again topped with memory foam.
Memory Foam is a high grade foam that "gives" it moulds around the body. But also will retain it's original shape when you get off. Memory foam is temperature sensitive, it will feel softer the warmer it is.

Memory foam is available in different grades or density, this grading is done by weight of the memory per meter cube (m3) from 60kg per m3 through to 100kg per m3. Sometimes know as V60, V80 etc....

Latex.

Latex is a natural product extracted from the rubber tree. It is more expensive then Memory Foam and has been used in beds for a long long time. It has a similar feel to Memory Foam and will function similarly as well. Added bonus of Latex is that it's not temperature sensitive. Usually the life span of Latex is longer then the spring it sits on.