Do you mean Global Entry? Because TT isn't a thing on its own AFAIK. There are a number of USCBP administered trusted traveler programs, namely NEXUS, SENTRI, FAST and Global Entry. NEXUS provides expedited C&I clearance between the U.S. and Canada. SENTRI provides expedited clearance at land borders between the U.S. and Mexico in registered vehicles. FAST (Free And Secure Trade) provides commercial truck drivers with expedited release on trips between the U.S. and either Canada or Mexico. All three of the above issue WHTI (Western Hemisphere Travel Initiative) compliant documents that can be used for travel by land and sea within much of North America and the Caribbean in lieu of a passport. The NEXUS card can also be used in lieu of a passport for air travel between the U.S. and Canada.

Global Entry on the other hand allows expedited C&I clearance at select international airports in the U.S., U.S. pre-clearance at select Canadian airports. There is also an agreement the Netherlands (with a separate application to FLUX, an alliance with the Netherlands' Privium program) that allows expedited C&I at Schiphol (AMS).

In June CBP began issuing Global Entry cards, which are WHTI-compliant documents that grant NEXUS and SENTRI benefits (the vehicle must still be registered in the case of SENTRI). NEXUS benefits only apply for entries into the U.S., but not into Canada.

Hopefully this will clear up some of the confusion about the different programs...