It's very unlikely that Uber and Waymo have radically different technology. The two companies probably differe only in business and testing practices- i.e. the environments and the conditions in which they are willing to test their cars.
Waymo simply seems to be more conscious about safety and therefore use its systems well within the safety limits of the technology. But, both companies have access to the state of the art (in the form of highly paid specialists) and you can't really expect one to be too far ahead of the other in terms of capabilities.
Edit: I'm guessing all this by comparison with results generally in machine learning and machine vision. With the exception of a big leap forward with CNNs in 2014, most improvements you ever see in the literature are in the order of a couple of percentile points at most so most systems differe by a very small margin. The same should go for industry entities using this technology in self-driving cars.