What are the US equivalent ranks to the Lecturer, Senior Lecturer, Reader (or Associate Prof), Professor ranks of the UK system? Is it correct that in the US system they are Assistant Prof, Associate Prof, Full Prof and Chair/Endowed Prof, respectively? I know that in the British system, there are further sub-levels in each of these ranks whereas in the US system there is no further gradation within each rank. So I am looking for only rough equivalence.
Edit: It would be great if a formal/informal reference which compares the two is also pointed out.