Without a union, employers have almost all the rights. They can change your pay and working conditions at any time as long as they do not violate certain laws, like the minimum wage. Any benefits you receive are at the discretion of your employer.
In a unionized work environment, your employer cannot make changes in your working conditions unless they are negotiated with you as union members. Any benefits or working conditions covered by your contract are protected by law.
When you negotiate your contract, you and your co-workers decide what kind of things could be improved at your work site and make proposals to your employer. Your employer is legally obligated to negotiate over most proposals that affect the quality of your work life. A union gives you strength in numbers to improve your pay, benefits, and working conditions.
In a non-union workplace, you can talk all you want with management — but management has the last word, take it or leave it.
When you are protected by a union contract, you can still talk all you want with management, but you don’t have to take “no” for an answer. Being part of a union gives you the right to effectively appeal unfair decisions and force your employer to correct unfair actions.