I realize models vary a little by country...

Lexus picked up my RX450h for its 30k km. service yesterday and dropped off a higher-end model of same as a 24-hour exchange. Mine is the middle model here in Switzerland. The differences and what I liked more or less are as follows:

1. The ventilated seats are much better and have better side support.
2. The air suspension keeps the back end under much better control and is generally a little more comfortable.
3. The Levinson audio is nice.
4. I really like the adaptive cruise control, though the main advantage is that it lets you know what speed you have actually selected, rather than guessing from the dial. Important for speeding fine management.
5. Memory seat on the passenger side.
6. The passenger-side parking camera is useful.

No change to the poor ergonomics of the multimedia system.