Peat is not coal. It can be called a stage in the process of getting coal. Coal the remains of ancient trees and plants that grew in swampy jungle in warm, humid climates hundreds of millions of years ago.
These trees and plants eventually hit the swamp water. During the process of decomposition of wood by bacteria the gases were getting out. With the time the gases were gone and formed a black mixture, mainly containing of the carbon. Later, under pressure from the mud and sand the liquid is out of mixture while viscous mass hardens turning to coal.
This process covering thousands of years from beginning to end. But the first stage of coal formation can be seen today. The Great gloomy swamp in Virginia and North Carolina and thousands of wetlands of Northern states of USA and Canada formed peat.
During the process of decomposition the plants are in these marshes, giving off large amounts of carbon. A mixed mass of brown twigs, branches and leaves produced after few years of this process. This is peat. When the water is pumped out of the swamps, peat can be cut into pieces, spread out to dry and burn.
Drying is necessary because the peat soil contains of 75% of water. In Ireland, there is a lot of peat while coal is expensive, more than half of farmers using peat as fuel. Other coal types are derived from peat. If you leave the turf where it was formed, it gradually turns into lignite or brown coal. It is harder than peat, but still quite soft and crumbly when transporting over long distances.
The next type of coal is bituminous or soft coal. It is formed in the earth from lignite and chemical changes under pressure for thousands of years. This is the most important product of the coal family. It burns easily and it is found in large quantities.
If bituminous coal is in the ground and subjected to sufficient pressure, it gradually turns into hard coal, or anthracite. It burns almost without smoke and longer than bituminous coal.