One big difference is that those two fatal accidents involving Tesla FSD were both cases of the Tesla driving into someone (a pedestrian in one and a motorcyclist in the other).

The one fatal accident involving a Waymo on the other hand was an empty Waymo that was stopped at a red light along with several other cars when another car (a Tesla, BTW) going just under 100 mph slammed into that group of stopped cars from behind, killing a passengers and a dog in one of them, and injuring people in several of them.