It’s important to understand the distinction between rejection and denial. A rejection typically indicates an error in your filing or fee payment that can be addressed and resolved. On the other hand, a denial represents a complete dismissal of your petition.
In the case of rejection, your employer has the option to file a new I-129 application to rectify the previous mistake. However, if your H-1B petition is denied, you will need to pursue an AAO (Administrative Appeals Office) appeal to challenge the decision and seek reconsideration by filing Form I-290B. You can also file Form I-290B, to file a motion with the USCIS, or a motion with the federal court.