OK.. A managed solution is one where you get good support, and one which will help you install any components you want (modules, scripts, etc) and take responsibility for any mishaps.
a non-managed solution is one where you get very little or no support, and in the case of RS they don't support you if install anything (libraries, modules, scripts, etc) and will not help except with the basic solutions. (i.e. if something goes wrong and you have added a module of your own then they will only support it as far as wiping your hard drive and re-loading all the software), and they don't give any backup solutions either.
James