Business is defined as value-creating activity by an individual or organization for profit. An example of a business would be General Motors (GM), a company that engages in production and worldwide sale of automobiles.
Commerce refers to the whole system of an economy that provides the environment in which business activities occur. The commerce in which GM conducts business would be the collective populations and economies of countries comprising the free world.
Occupation is a person’s means of making a living. Associated and closely related terms are as follows:
Employment = being under service of another for hire
Job = regular activity performed for payment
Vocation = occupation to which an individual is especially drawn
Profession = a vocation requiring specialized training
Career = a life course of employment activity
To answer your question, business organizations perform value-creating activity within an environment of business commerce. Individuals of various occupations work for hire as employees of the business organization (employer). They perform the work that creates the value produced by the organization. Workers having the various occupations within the business perform the services or make the products that constitute the output of the business organization.