Fading generally is a signal loss either in amplitude or phase due to sudden changes in Channel response.
Large scale fading " Shadowing" concerns about large distances effect so, its affect appears clearly incase of the displacement of either the Transmitter or the Receiver. The most clear example for this case is the RF reception for a Car or a moving vehicle where the signal is influenced by Multipath phenomena where the transmitted signal is received from more than one path.
However Small scale fading is concerned about very small changes in the position of Transmitter or receiver in order of the wavelength as this affect greatly the received frequency due to doppler effect so as the speed of the vehicle increases as the frequency is more rapidly changing and it can be described as fast or slow fading AND flat or slow fading.