Clarity between Principal Applicant and Petitioner name


My sister applied I-130 for me. My I-130 got approved. I had shifted to a new address. Now my sister called NVC to update my address and it was updated but the city still spelled wrong. Now I want to update NVC the correction of the city name by giving an email. I am not clear with Principal Applicant and Petitioner name.

My understanding is Principal Applicant - My name

Petitioner Name- My sister name.

Is my understanding is correct. Please reply.