NEXUS is for US-Canadians citizens crossing each other borders.
Here's NEXUS program link:
What Are The Benefits Of NEXUS?
Individuals approved to participate in NEXUS receive an identification card that allows them to:
- Receive expedited passage at NEXUS-dedicated lanes, airport kiosks, and by calling a marine telephone reporting center to report their arrival into the United States and Canada; and
- Cross the border with a minimum of customs and immigration questioning
- Use of Global Entry kiosks
The NEXUS program allows pre-screened travelers expedited processing by United States and Canadian officials at dedicated processing lanes at designated northern border ports of entry, at NEXUS kiosks at Canadian Preclearance airports, and at marine reporting locations. Approved applicants are issued a photo-identification, proximity Radio Frequency Identification (RFID) card. Participants use the three modes of passage where they will either present their NEXUS card or have their iris scanned and make a declaration.
U.S. Customs and Border Protection (CBP) and Canada Border Services Agency (CBSA) are cooperating in this venture to simplify passage for pre-approved travelers.