Societies with command and free market economies answer the basic economic question "What goods and services should be produced?" in different ways. What is the main difference?

The main difference is who controls the factors of production and economic activities

Explanation:

In a command market economic which is also known as a planned market economy the government controls all factors of production and economic activities like what goods and services are produced and how they are distributed and sold in the open market.

while in Free economy  the factors of production and economic activities including the prices and profits to be made are been controlled/regulated by the demand and supply of goods and services in the open market with little or no Government intervention these kind of economies can also be seen/known as Black market economies

jewish people, gypsies, and political opponents.

by 1880, germany had more rail lines than great britain and russia.