yea, JMSS is more science based, whereas SEHS has a more holistic approach. if you're 100% sure that you want a career in science, then JMSS is the place to go, but if you want to stay flexible, then try again for SEHS if you don't get in the further rounds.
it would kind of be a waste of time and effort if you went to JMSS and decided that you don't want to continue with science, so touring the school and even talking to some of their students would be a great idea