True. Choosing between the two languages usually comes down to their library ecosystems - or more bluntly, to Rails on one hand vs NumPy on the other.
Nonetheless, it's still common for people to talk about the relative performance of the two languages, and to claim that Ruby is slower than Python. As someone who's actually tested this, it hasn't been true for 15 years.
In every test I've done, Ruby has been faster than Python. In my experience that's been the case since Ruby 1.9, with the move to YARV.