They use the RIAS here as well (I think the entire state does) and it ended up being an underestimate for my son. I believe thats because of training of the tester in the area of really gifted children and the fact that it's a super quick test with ceilings. The results from it did give us the extra push we needed to seek someone with more experience and knowledge on gifted children though! The school tester did not give much information other than that he qualified for the gifted program (what there is of one) and that he had really high scores.
I hope you are able to get some resolve with the two sets of scores and at least solve a piece of the mystery. Don't pace too much while waiting:)