Yes, they are completely different. "Woher" asks for the origin, "wo" asks for the location of something. Woher kommst Du? / Wo kommst Du her? Where are you from? Woher weißt Du das? Where did you learn that? Wo liegt China? Where is China located? Wo wohnst Du? Where are you living?

yes. Woher = from where wo = where. is clear enough? ;-）

In addition to Knut's explanation, there is another similar word, "wohin" which tells about the goal of the movement. where are you going ? wohin gehst Du? oder wo gehst Du hin (like the example of Knut) her is always towards the viewer hin is always away from the viewer