What is white coal called? What is brown coal called?

In general context, white coal is called ‘hydroelectricity’.
Hydroelectricity is called ‘white coal’ because it is produced by dropping water from a height and generating electricity with the help of turbines. That is why it is called ‘white coal’. Any coal is a form of energy fuel. Hydropower is only a form of fuel, hence it is called white coal.
There is also a substance called white coal, which is a modified form of fuel made by drying cut wood over a white fire. This modified form of it is different from charcoal. White coal was used in the 16-17th centuries. It produced more heat than wood. This coal is mostly used in cold climate countries of Europe and America.

Brown coal is called ‘lignite’. In the second stage in the process of formation of coal, lignite is brown in colour, hence it is called ‘brown coal’.