What is the key difference between a market economy and mixed market economy

Market Economy:

No government intervenes in decisions related to economies. private ownership decide for all production. Consumers himself decide what should be produced in the economy and he can do this by purchase he made. In Market economy prices determined by market forces.

Mixed Economy:

Most of the world economies preferred a Mixed economy. It is a mixture of a command and a market economy. The mixed economy is regulated by Government regulations.

The statement that is a key difference between market economy and mixed market economy is this: Market economies have no government influence while mixed market economies are loosely regulated by the government. Hope this is the answer that you are looking for.