In most cases, government employees are treated differently than employees of private employers. In most situations a government employee has more options and avenues to pursue when there is a problem such as being bypassed for a promotion, being discriminated against, or being terminated. This is especially true for employees of the federal government.
An at will employee has very few rights, except for the laws preventing discrimination, if his or her employer wants to terminate his or her job. After a probationary period, government employees are different. They have several options if they are faced with wrongful termination.
In our current economy, where employee benefits are becoming fewer and fewer, government employees are in the better position regarding benefits and being treated fairly compared to nongovernment, at will workers.