Threshold vs 1hr

I was always under the understanding that these were on in the same. Xert has my threshold at 386 but my 1hr power at 369. Which number do I use to structure workout and calculate the difficulty of a race?

If you use Xert for your workouts, all you workouts are structured using your threshold power since this is your point of equilibrium. The reason for your 1-hour power to be lower is due to your above average reliance on endurance energy stores in generating high power efforts. These are affected more during longer activities, hence for you, your 1-hour power is well below your threshold power.