That's how I see it as well, my parents have a slightly newer Audi Q5, and while it's a lovely drive for sure, two things come to mind; 1) The Lexus is much more quiet, and that's not due to the Audi being loud by any stretch of the imagination, the Lexus is just super quiet, even when using the petrol engine. 2) The Lexus is quite a bit more comfortable imho, the seats are particularly great. The suspension isn't quite as firm as the Q5, but it certainly doesn't come across as flimsy, just a slightly more comfortable ride overall.
Might wanna add that I've got a RX 400h, so I reckon it's even better in your RX 450h 🙂