I don't know why this image is not directly on the Rhyzer details page from Joola but here is the difference side-by-side.
Rhyzer 43/48 vs Rhyzer Pro 45/50 topsheet:
I don't know how the rubber of the Rhyzer Pro 45 will look like...anybody got information on that?
You can search for "Glas fibre" on stervinou.net which is a database for blades.
It's not up to date nor complete but it can help though.
Here's the result:
