How is it that a multi-stage centrifugal or reciprocating compressor can have 2 stages rotate at the same RPM and produce different outlet pressures by only having different impellers or pistons?

In a multi-stage centrifugal or reciprocating compressor, different stages can operate at the same RPM but achieve varying outlet pressures due to the design of the impellers or pistons. The impellers in a centrifugal compressor can have varying diameters and blade geometries, which affect the velocity and pressure of the gas being compressed. Similarly, in reciprocating compressors, pistons with different diameters or stroke lengths can compress the gas to different pressures. This allows each stage to be optimized for specific pressure requirements while maintaining a consistent rotational speed.