There are certainly differences between the various accessory rails out there. The slot on a Glock rail is narrower than that of a 1913 Picatinny. The rails on Smith & Wesson's TSW series are also unique. Fortunately, when I bought my TLR-1 lights (I have two), they each included different inserts for different rail types. I have one set up for my Glock, and another fits a Picatinny rail on my AR15.
Specific to your situation, though I've not used a rail on a Ruger SR series pistol, I'd guess that it's compatible with either a Glock or Picatinny type rail.