Is cocoa powder the same thing as chocolate powder? No. Chocolate powder is ground chocolate, which has sugar and other ingredients that cocoa powder does not have. no cocoa powder is pure and chocolate powder is processed.
A knot is used to join two ropes together or a rope to itself while a hitch is used to tie the rope to another object, such as a pole.
And, I too have considered a hitch as a 'knot' used to attach a rope to something else, but I'm not sure that's definitive enough. For example, a bowline or F8 can be used to attach a rope to something, but I've never heard/read of either being a hitch.