PLEASE don't use the Tesla website. It is not for trip planning. The car's computer is way more accurate.
However the car's computer is also not very efficient with the charging times on long trips. It stays at chargers for too long. You should be stopping more often and charging for shorter times.
I would trust ABRP for planning your whole trip then use the car's computer to plot to each individual supercharger stop.
I've noticed this with the Model X. The in car trip plan often had me at close to 20% at the next Supercharger. It was really inefficient compared to a shorter charge.
The weird thing is that it would estimate 5% for the next Supercharger, but it would jump by ~5% when I unplugged. Then it would gain another 7% or so on the estimate while driving.
The Y seems to estimate arrival percentages more accurately.