The PSAT 8/9, PSAT10/NMSQT, and SAT are on the same scaling, which is why there is a lower ceiling on the PSAT/NMSQT (and even lower on the 8/9). The idea is that the PSAT scores estimate the scores you would get if you took the SAT at that same time, and thus make it simpler to track progress across tests.

...pronounced like the long vowel and first letter of the alphabet...