B.B.
I used to teach in a charter school. One of the things you are going to want to check out are the "extras" - school psychologist, reading/math specialists, TAG team, ESL, special education teachers/specialists/resources. Those things are not required, so if the charter school is in its early years, or experiencing some financial difficulty you may find less than adequate resources in those areas. When I taught in the charter school, we did not have ANY of the resources I listed...it was super tough. Especially in an elementary school, as the younger years are when you start to realize that the child may need some "extras".
The charter school has to abide by the state public school laws - minimum number of hours/day, minimum days/year, standardized tests. The biggest difference is that the charter school is run by a board of directors rather than the city/town board of education. There are pros and cons to that.
Just do your homework, talk to some parents of kids who are already in the school. Talk to the principal/director about budgets and programs.