Hey,
The two degrees had some similarities. Anatomy & physiology modules are more or less the same. Other modules such as biomechanics are similar but taught from a different angle. Then the Physio degree has some very different modules such as neurology & respiratory, whilst sports rehab have more sports science based modules.
Like I say, both interesting degrees. Sports Rehab definately more fun & interesting to do in the hear and now BUT Physio has longevity.
If you want my honest advice/opinion - do Physio as it offers a more varied long term career path - you can still specialise in sport now, but you can career paths later in life if you want!
I spend first half of career in sport but have now worked my way up to be an ESP in NHS!
Good Luck!