Both: Active Noise Cancellation
Apple appears to have put the same Active Noise Cancellation and Transparency feature into the Beats Fit Pro that the AirPods Pro originally became famous for.
To be clear, Apple hasn’t placed the Beats Fit Pro at a disadvantage. There’s every indication that the ANC and Transparency features are identical to the AirPods Pro, and every reviewer has basically confirmed this in their own listening tests.