Compared to the 370Z, the 2023 Nissan Z's body gets all new sheet metal and an aluminum hood. Aerodynamics were improved to reduced rear lift, front lift and streamline airflow along the side of the vehicle. They also went with an external slave cylinder, bottom exhaust setup for the oil cooler (allows much more air flow and avoids one more layer of radiators up front) and likely similar changes elsewhere.

There's probably a lot that I am missing, so feel free to include them below.

2023 Nissan Z Body & Aerodynamics
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External Slave Cylinder
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Oil Cooler
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Here you can see that the brakes have been carried over from the old model.
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