How can I get compensated for the job I am performing not the title they gave me?

Barring a contract which provides for it, such as a union contract providing wage scales for people depending on title, an employer has no obligation to compensate employees equally.  C.C. Sabathia is paid a lot more than Luis Severino.  The employer is obligated, however, not to discriminate on the basis of race, gender, religion, etc.  If you believe that you are being discriminated against on the basis of any such protected characteristic, you may have a valid claim, but otherwise not.