Although related, a Compensation Agreement is quite different from an Employment Contract.
After an employer has offered someone a job, they create an Employment Contract to outline the employment terms, such as the recruit's job title, responsibilities, and hours, as well as details about the initial compensation an employee receives when they begin their employment.
A Compensation Agreement is usually introduced at some point during the employment term, such as after a probationary period or annual review, to outline any changes in wage, salary, or commission. The agreement simply records the employee's updated compensation terms.
As stated previously, a Compensation Agreement is a supplemental form to an Employment Contract and does not replace the entire thing.