The ES300 and Camry V6 share platform and powertrain, but they are constructed differently. The Lexus uses layered sound dampening sheet metal which makes it exponentially quieter. The Lexus is also built in Japan, while most Camrys sold in North America are built in the US.
As far as tires go, Lexus uses/recommends tires with soft compounds to reduce road noise. This means softer rubber that wears faster. You can use any tire of the correct size and rating (Z, H etc), just be aware that tires sold with 80K mileage warranties are very hard and make more noise on the road.