The decision to hire an employee or employees is a big one because of the responsibility it entails. When you hire someone you are agreeing to provide him or her with work and pay, whether you have that work or not, unless they are temp workers or subcontractors. If they are subcontractors, you cannot, by law, ask them to show up at certain hours or work for an hourly wage. Before you work with a subcontractor, be sure to review the laws with your accountant and lawyer. If you violate the legal description of a subcontractor relationship you may be liable for back taxes, withholding, worker's compensation and other deductions you should have taken.
Temporary employees work for an agency that takes care of all their payroll and insurance needs.
You contract with the agency for their workers. While it sounds ideal, it is expensive and you will discover that it's difficult to obtain skilled workers. Permanent employees are people in whom you invest a considerable sum with the hope that the work they do will more than justify the cost of having them. Your expense is not just monetary. You must train them and provide a safe environment and various perks, including medical insurance, vacations, etc.