This was from a Science Olympiad remote sensing test. I know that each will reflect different wavelengths of light and that there's also a lot of overlap...I just don't really know what the exact (or approximate) differences are.
As for differentiating 'snow' & 'ice', it becomes much more difficult. 'Glacier ice' is quiet different from 'sea ice', which is again very different from 'freshwater ice / lake ice'. As such, with no additional information on the exact topic, the answer either has to focus on one case, or simply focus on workarounds to circumvent the nitty-gritty details. One possible "answer" would be to assert that ice is surface water that has turned solid, and then rely on water body mapping.