WS2818 is an 8-bit LED Driver IC for RGB Pixels from WorldSemi. The IC is separate from the LED package. It has data backup in order to pass on the data signal past a dead/defective pixel.
WS2813 is an 8-bit LED Driver IC for RGB Pixels from WorldSemi. The IC is integrated into the 5050 LED. It has data backup in order to pass on the data signal past a dead/defective pixel.