Amateur
In some sports (e.g. tennis or football) in the past, amateurs and professionals would not compete against one another. This was not always because amateurs were thought to be not as good as professionals. In some countries, such as Great Britain in Victorian times, this was because of social class distinction. Amateur cricketers were rich gentlemen from the upper classes who did not want to associate with people from lower classes.  This attitude slowly changed during the 20th century.