MSDN에 다음과 같이 쓰여져 있습니다.

The ExcludeUpdateRgn function excludes the update region from the clipping region for the display device context. This function is useful when drawing in a window other than when a WM_PAINT message is processing. It prevents drawing in the areas that will be updated during the next WM_PAINT message.

The ValidateRect and ValidateRgn functions validate a portion of the window by removing a specified rectangle or region from the update region. These functions are typically used when the window has updated a specific part of the screen in the update region before receiving the WM_PAINT message.

MSDN의 설명만 봐서는 ExcludeUpdateRgn 과 ValidateRgn 의 차이가 무엇인지 구분하기가 힘든데, 그 차이점이 무엇인지 아시나요?
그리고 Update Region 과 Clipping Region의 차이점은 무엇이지요?