We hear about regular employees all the time. The Labor Code explicitly defines regular employment. However, casual employment is given a negative definition. That is, if you are not a regular employee, project employee, or a seasonal employee, then you are a casual employee.
This may be confusing. Casual employee simply means that you work is not usually necessary or desirable to the business of your employer.
Things get clearer by giving examples. A carpenter fixing some tables and chairs in a restaurant is a casual employee. A truck helper in a mall might be a casual employee. A janitor in a tech company is a casual employee. You get the drift.