What is the major difference between the US. democracy and Great Britain?

United States:

In the United States the chief executive is directly elected by the people.The President is not a member of the legislature and neither his cabinet members.Separation of power.Fixed term elections.

Great Britain:

In a parliamentary government, the executive derives from the LegislatureThe executive is formed by the party with most number of seats.Fusion of powers.Date of election is called by the PM.Hope it helps!

The amendment process.