Wheels are considered to be hub centric if the center bore of the wheel is the same size as the hub diameter of the vehicle. This allows the wheel to be centered by the hub. If the center bore of the wheel is larger than the hub of the vehicle this would be considered to be lug centric as it would be centered on the hub by the lug nuts.
Hub Rings can also be used to make a lug centric fit wheel hub centric by filling in any gap between the hub of the vehicle and the center bore of the wheel.