Michael Schoch, Answers questions on Noodle
I'm by no means an expert on international schools, but I've assembled a few articles and sites that may give you a clearer picture of what these institutions offer and how they differ.
The student body at any school is going to vary greatly depending on location, funding, and curricular focus among other things. Most if not all of international schools will focus on language and literacy skills, as well as critical thinking in a global context.
To get a sense of the nuances between different schools I recommend looking over this list of international schools in NYC. It includes both public and private institutions.
Another great resource is this article on IB and Cambridge programs. It gives an overview of what international schools are and how they're beneficial.
Hopefully these links will give you all of the basic info you need to move ahead and make great decisions. Feel free to write back any time if you have more questions or need help. Good luck!