The CB has changed the scores for all of it's (P)SAT family of tests to be on the same scale. So PSAT 8/9 scores are supposed to approximate what the same student would have obtained on the SAT, if it were to be administered at that same time. This does also mean that the possible scores obtainable on the PSAT 8/9 are not exactly the same as the SAT, as both its max and min are lower (240-1440). So the scaled score compares students to college-bound seniors, though with a lower ceiling.
Then there are grade-based percentiles, which compare students to their grade-peers. E.g., the score f&esmom cited above is about the 97th %ile for 8th graders in Fall 2017, and the 92nd %ile for 9th graders in Fall 2017.
One hopes you both received this document with your DC's scores:
https://collegereadiness.collegeboard.org/pdf/psat-8-9-understanding-scores-fall.pdf
