Is there a big difference in Connections Academy vs. Indiana University High School or others?

My son will be attending our local technology center next year to study pre-engineering. He will take algebra II, chemistry, & a pre-engineering elective there this year & next year will be pre-calc, physics, & the elective. He will need to take the rest of his high school classes online. Our state offers several virtual schools and when looking the highest ACT score is the Connections Academy. He could attend this school for free. I have also looked at Indiana U HS. It would cost $256/course. My son’s current brick & mortar school isn’t very rigorous, so we are making this change to hopefully help him be more successful in college. He will also play baseball in college, so will have to balance that as well. My question is, is there a big difference in these two schools that would make the Indiana U. worth paying for or would the Connections Academy that is no cost be pretty similar? I don’t mind paying if there’s a big difference. Also if there is another school that you would recommend, please let me know. I can’t afford Stanford or some of those, but can afford something similar to Indiana. Whichever school, I need to make sure that they are NCAA approved. He will be a sophomore next year. Our state allows concurrent college enrollment beginning junior year & 6 hours/semester free tuition senior year.