Sorry to be so long responding. The radio installation occurred at a bad time. Office move took priority.
Thank you for the explanation, LC. That helped when I called local installers

I still don't understand why there would be two different wiring harnesses - radio delete or not radio delete - but guess that doesn't matter. I just need to find the right harness now.
LC, you'll get a kick out of this. I called the local Hyundai dealership hoping they would offer aftermarket wiring harnesses for this task. They don't

but I did ask the Hyundai guy about Radio Delete. He had no idea what it meant. I suggested that might be when a car comes from the factory without a radio, and he thought that might be reasonable.
I'll restart my search tomorrow for the correct harness. Tessa's car is NOT Radio Delete so I need the harness that doesn't have that pin structure. I do need to find out if her car is domestic or import production - apparently that matters for this.
Other good story that came from this effort - Tessa's car was returned to her without a radio while I search for the right harness. But the mechanic / installer that took the radio out also didn't put back the dash "faceplate" which still contained the clock, heating vents and hazard button. Without the hazard button, she had no turn signals. Without looking at this myself and being out of town, I called the mechanic to see if he could "repair" her turn signals. He said that he was swamped and wasn't sure what it would take, could we leave the car for the day. One call to the brother-in-law and Tessa figures out that the hazard button, vents and clock can all be pushed out of the faceplate and be easily reconnected to the wires sticking out of her dash. I think I have a budding independent young lady on my hands. Pretty proud of her!