Here is an article comparing sensor types: http://www.templetons.com/brad/robocars/cameras-lasers.html

The lidar that google uses provides a huge amount more information. Add that to the detailed maps that the google vehicle uses and it's pretty clear that these vehicles aren't really trying to do the same thing. Google's trying to handle fully driverless operation but Tesla's going for a more immediately commercializable middle ground.

It's my understanding that Lidar is a lot more sensitive to bad weather