Hi Morst,
Hope you're well.
From the intertubes:
"Change Speed, affects both Tempo and Pitch." "Change Tempo" states "Change Tempo without Changing Pitch."
I use change tempo in Audacity so that I don't by accident change both tempo and pitch.
Just wondering if rx7, being modern and high quality as far as I've tested, might have a better sounding algorithm, though Audacity's change tempo is well regarded.
~Chris