opengl - When is glClear executed?

Question

Consider these commands in OpenGL in given sequence:

glClearBufferuiv(GL_COLOR, 0, clearColor);
glClearBufferuiv(GL_DEPTH, 0, &depthValue);

..

glDraw(...)

Does the clearing of the default frame buffer happen immediately after clear command ? Or is it done during the draw call? (If its done during the draw call, then if I skip draw, will clearing of these buffers be skipped?)

Does the order of clearing color and depth buffer match the actual order specified? or the driver is free to implement it however it wants.