People will do things as they have always been done. Traditional societies depend upon personal characteristics for social organization. Those include who you are, your status or your family's status. This determines what job you will do and how you will live. Command economy is one in which decisions about production, distribution and consumption are made mostly by the government.
People do things for the good of all society.
Command economies are organized by rules, and those rules are decided upon by a centralized authority. For example, the government decides what goods will be produced and how much will be made. It is impersonal, in that individuals in the society probably don't know the individuals in the government who make the decisions. Market economy is one in which decisions about production and distribution are made mostly by individuals and companies in the economy. People do things because they see the potential for benefits, such as choosing a job with the salary that allows you to live the lifestyle you want.