The difference between bargaining and non-bargaining federal employees is how negotiations are handled. Unlike bargaining or represented employees, non-bargaining employees can't join others to negotiate employment issues.
Bargaining employees are represented by labor unions or other labor organizations that negotiate with the government to ensure favorable employment conditions and fair wages. When they reach an agreement, it's known as a collective bargaining agreement. The employer is legally obligated to follow the terms of the agreement, which typically covers wages, overtime, safety policies and other work-related issues.
State regulations allow companies to exclude certain types of employees from bargaining. The type of employees that can be excluded varies depending on the state and the industry. Short-term and temporary employees commonly fall into the non-bargaining category. Non-bargaining employees aren't represented by a union, therefore the collective bargaining agreement won't apply to them.