1: I assume you mean Fate route Rin, not a composite Rin as you have stated here.

2: They're the same. Rin's combat strength changes in Heaven's Feel, UBW and Fate Rin have the same abilities. Unless you mean she gets Saber.

1-From the first route Fate/stay night.

2-They're not, imho. I feel like Rin from SN is stronger than UBW's, and it's showed all throughout the anime.

They are the same person with the same training, same expirience, same supplies. The only difference is a 2 week period where she gains combat skill, but both gain that skill, only Heaven's Feel has notably different combat ability.

Stop calling her Rin Stay Night, Stay Night is the name of the entire work, not the route. The Routes are Fate, Unlimited Blade Works, and Heaven's Feel. The first route is named Fate.

Names dont matter when most people know them from the OG first anime. Not the VN.