There's more to it than that. Firing an employee has more legal consequences to a company than having them resign. For example, the company will likely have to

There's more to it than that. Firing an employee has more legal consequences to a company than having them resign. For example, the company will likely have to pay unemployment taxes to cover the unemployment benefits an employee is likely to receive. Resigning a position also allows an employee to save face and will be documented in their employment file and provided for reference checks from future employers.