Form I-797 is form that U.S. Citizenship and Immigration Services (USCIS) sends as notice of approval of a petition or an application. It is called “Form I-797, Notice of Action.”
Form I-797C is a notice that USCIS sends to a petitioner or an applicant that has filed a case. USCIS uses the I-797C, Notice of Action to communicate certain information. The I-797C can be a receipt notice, a rejection notice, a transfer notice, a response to a motion to reopen, or an appointment notice. The appointment may be for biometrics (fingerprinting and photographing), for an interview, or for an interview rescheduling.