How do the Nexus and TSAPre / Global Entry programs and access relate and interact?
TL/DR: for bullet points, scroll to the bottom.The relationship between NEXUS, SENTRI, Global Entry, and TSA PreCheck can be confusing. The relationship works like this:The main benefit of NEXUS membership is expedited customs and immigration clearance when crossing the border between the United States and Canada. When crossing by land, NEXUS members may use dedicated processing lanes (though it's important to note that it is against NEXUS rules to use NEXUS vehicular land lanes when traveling with someone who is not a NEXUS member). NEXUS can be used when crossing the border by sea in a similar manner. When traveling by air into Canada from any origin country, and when entering the United States via a US air pre-clearance facility in Canada, NEXUS members may process through dedicated NEXUS lanes, and use NEXUS kiosks. NEXUS kiosks take the place of the customs declaration form except in extraordinary cases, although Canadian residents may be required to fill out a traveller declaration card if required to pay import duty. Additionally, NEXUS members clearing security at certain Canadian airports receive expedited screening through dedicated lanes. NEXUS members can expect decreased scrutiny when processing through NEXUS border and security lanes by virtue of their background check.SENTRI is in much the same ilk as NEXUS, but rather than dealing with the US-Canada border, it concerns land crossing into the United States from Mexico. SENTRI members may use of dedicated vehicular and pedestrian processing lanes when entering the United States, and the SENTRI Dedicated Commuter Lanes, which are designated for the exclusive use of SENTRI members. When crossing into the United States from Canada at a land border only, SENTRI members may use NEXUS lanes to enter. SENTRI members can expect decreased scrutiny when processing through SENTRI (and NEXUS, when eligible) border lanes by virtue of their background check.Unlike NEXUS and SENTRI, Global Entry is not border-specific. Rather, Global Entry can be used by Global Entry members at most international airports in the United States to pass through immigration and customs. Like NEXUS, Global Entry uses a kiosk system, but a fingerprint-based identity verification. Global Entry can also be used when entering the United States at the Canadian and Mexican borders by land to receive expedited customs in the NEXUS and SENTRI lanes, but not the SENTRI Dedicated Commuter Lanes. Global Entry members do not need to complete customs arrival documents. In locations where Global Entry is temporarily unavailable, Global Entry members get front-of-line privileges. Global Entry members can expect decreased scrutiny when processing through Global Entry lanes by virtue of their background check.TSA PreCheck is a Trusted Traveller Program, but it is not run by Customs and Border Protection, rather, it is administered by the TSA. It grants its members expedited screening at US security checkpoints which may include metal detector screening with shoes and light jacket on, as well as in-bag screening for laptops and liquids. It grants no border-related privileges.Still with me? Okay, this is where it gets complicated.NEXUS and SENTRI members can be entitled to Global Entry membership (most are), but some are not, by virtue of the programs' differing requirements. People who have NEXUS and/or SENTRI and are eligible for Global Entry are automatically enrolled, and receive Global Entry benefits seamlessly with their NEXUS and/or SENTRI memberships. That means that as a NEXUS member, I can walk up to a Global Entry kiosk, stick in my Passport, and process through just as a Global Entry member would. This also means that at US pre-clearance facilities, I can choose as a US resident whether to process through the Global Entry or NEXUS kiosks, as I am eligible for both.However, Global Entry does not grant NEXUS or SENTRI membership, and Global Entry members trying to use NEXUS kiosks in the airport, or enter Canada via NEXUS lanes would be turned away. Similarly, while Global Entry and by extension NEXUS members can use dedicated expedited customs lanes at the Mexican border, they would be turned away from the SENTRI Dedicated Commuter Lane, which is reserved for SENTRI members only.Members of Global Entry, NEXUS, and SENTRI are eligible for PreCheck screening, but they are not enrolled in the PreCheck program. They receive PreCheck screening as a benefit of their individual memberships, not just Global Entry, so a NEXUS member who is not eligible for Global Entry is still eligible for PreCheck screening. The PreCheck program provides PreCheck screening to its enrollees with the same frequency (virtually all the time), and a PreCheck member will have the same experience as a member of the three other trusted traveler programs. The lack of actual cross-enrollment in the PreCheck program by these programs is a semantic difference to travelers.So, to summarize:NEXUS does not get you SENTRI, and SENTRI does not get you NEXUSSENTRI or NEXUS probably gets you Global EntryGlobal Entry includes some benefits which overlap with SENTRI and NEXUS when entering the United States, but does not grant membership in either program.SENTRI, NEXUS, and Global Entry get you PreCheck screening, but not the PreCheck programThe PreCheck program just gets you PreCheck screening