I don't really care who the manufacturer says their car should compete against. Camry/Avalon share the same platform as well as the Maxima/Altima. All are FWD.
The Avalon is significantly larger than the Camry - and significantly more expensive too. That puts it out of the Camry's segment, by industry definitions.
The Maxima and Altima are on separate platforms, and the next-gen Maxima is going to be on the FM platform - and RWD.