While both are similarly sized/configured, they sound very different in the mid range and tweets.
Both have very good, clean bass resolution in my opinion.
Paradigm gets a big nod for smoother and better defined mids. About the same for the highs. The soft dome of the Polks is very nice but a bit too laid back
(again for my tastes) somebody else may vastly prefer that more relaxed highs.
The Studio 100 V5s have very clean/clear highs without being harsh and are easy to "shape" by altering toe in/out.
The Paradigms are pretty directional that way.
The Polks also require a LOT more power to open up where the Studios are more consistent with dynamics.
Scott