What are the differences between high voltage switch gear and medium voltage switch gear?

a switchgear is a term used with the electric power distribution system, and is basically a large switch or set of switches used in switching very high voltages at very high currents and can occasionally have arc overs, though they are ushually supressed by a number of safety measures. medium voltage probably being under 100KV but more than 5KV, but that's just a guess as to voltage ratings...