To my understanding, "Aero" is just the technology behind, featuring transparency, 3d and other fancy stuff. The rest are just themes using it to some degree, i.e. with or without the glass effect. Just like GDI+ and GDI+ applications, both are needed to see the nice result, but they are not the same thing. So if home basic supports the technology but only lacks the theme, it should be somewhat trivial to add it, but if the core is missing as well... then it might require some more work