Tyrolia/Head complicates their binding line by having 3 different plates to mount the bindings to the ski - Railflex, FreeFlex and Power Rail. The bindings are the same on all three.
Almost all Head skis come with Head branded bindings, but, the bindings are made by Tyrolia. The number in the binding, ie 10, refers to the highest DIN number, so, a Hea /Tyrolita PR 11 would have a maximum DIN release setting of 11. Your girlfriend probably needs no more than around 4 DIN, so there is no benefit to getting a bindings with higher number. I, and many others in Epic, have skied the Head/Tyrolia bindings for years with no issues. There is very little distinction among the various bindings available. I believe the LR indicates that binding uses the Railflex plate. Your FF bindings are the same as I use on 2 skis including the original Head SuperShape.
I agree with Stevesmith7 that there is a slight advantage to the PR series in that the bindings can be moved forward or backward to permit getting the boot in the perfect spot. Newer skiers really don't need that precise a level of adjustment. If the price is right, have the LR 9 installed, go ski and enjoy it.