These are examples of frozen motion and semi motion photographs. In the first photo to the top, my subject is in motion and the background is frozen, a blur like effect from the camera being present is what depicts something/someone is moving in the image. This photograph worked best as an example of frozen motion. In the second photo on the bottom, the image shows my subject is still but the background is blurred as if to suggest there was motion going on and this is signified by the blurring so this was used as an example of Semi-motion.
Just to be clear, both of these are in that semi-motion state. If you want one that is truly frozen, we should see no motion blur anywhere and it would be shot with a high shutter speed to achieve that result.