There is not a big difference between the PSAT and SAT as far as the questions and test format, though the PSAT is a shorter test. The big difference is that once you hit 9th grade, the SAT scores stay on your College Board record, so if a college requests you send all scores, they see your 9th grade score (which is likely to be lower than an 11th grade score).
You say you are in Toronto. Is your child a Canadian citizen or a US citizen? For NM purposes, you need to be a US citizen or a permanent resident of the US. You can be living abroad, take the PSAT and qualify for NM, but only if you meet the above qualifications. And those living outside the US typically must meet the highest qualifying cutoff score.
