What's the difference between USCIS and the National Visa Center (NVC)?

USCIS and the NVC handle different stages of the same overall process, and mixing them up is one of the most common sources of confusion.

USCIS (U.S. Citizenship and Immigration Services) is a Department of Homeland Security agency. It reviews and approves the initial petition (like Form I-130) that establishes a qualifying relationship or basis for immigration.

The NVC (National Visa Center) is run by the State Department, not USCIS. Once USCIS approves a petition for someone who will immigrate through a U.S. embassy abroad (rather than adjusting status inside the U.S.), the case moves to the NVC, which collects civil documents and financial forms, then schedules the actual visa interview at the embassy.

In short: USCIS approves who qualifies, the NVC handles document collection and interview scheduling for cases going through a consulate abroad. They're separate systems with separate case numbers, so a receipt number from USCIS won't work on the NVC's own portal (CEAC), and vice versa.