An employee is a person who works for a company. He was hired by this company and is paid by it. However, one can also have a job with a municipality, for example in street cleaning or in a hospital. The opposite of an employee is above all the self-employed, that is, someone who is his own boss.
In the past, it meant something else: a white-collar worker was the opposite of a blue-collar worker. White-collar workers worked "in their heads", blue-collar workers with their bodies. White-collar workers had a better education and often worked in an office. Labourers, on the other hand, got dirty at work, for example outside or in a factory. Some white-collar workers therefore thought they were better.
Today there are hardly any differences between white-collar and blue-collar workers. In Switzerland, for example, white- and blue-collar workers have exactly the same rights. Also, white- and blue-collar workers can join associations or trade unions in the same way. There are also no longer any differences in pension provision.