Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Communication Breakdown; Confusion
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Chart Or Publication; Human Factors
While enroute to GTF; the CA (Captain) who was PM (Pilot Monitoring) requested direct DATSA with Center in order to set up for RNAV (RNP) Z RWY 21. As we neared DATSA; Approach Control gave us a vector towards the northeast for sequence. After a few minutes we were given a vector towards the southeast and the controller asked if we still wanted the RNAV Z Approach. We said yes.  He gave us a clearance direct to 'DRIFT'. I pushed DTO (Direct To) and used the FMS to fly direct to the fix DRFTR (I thought the controller was simply using a different pronunciation of the same fix). Shortly after; the CA realized that there was another fix on the approach: DRYFT; which was not in our flight plan in the FMS since we had used DATSA as our IAF. He queried the controller who confirmed that he had cleared us to DRYFT. At this point I had the airport in sight and  we requested a visual approach. We were cleared for the Visual to RWY 21 and performed a stable visual approach.The lesson I learned is to listen more carefully to the spelling of the fix the controller is giving us and not just assume it's the fix that sounds close to what he said. I recommend that one of these two fixes DRFTR and DRYFT be changed to something different. These two fixes are close to each other on the approach and the spelling and pronunciations are similar enough to cause confusion.
Air carrier Flight Crew reported two fixes with similar names close together.