Alright look the client is property of jagex. Jagex obfuscates the client to protect their client code to be easily stolen. Now this is where rsps come in.
People de-obfuscate their clients to get the code. But the thing is you cant deobfuscate it perfectly. For example say jagex would make an integer "modelId" and then they obfuscate it and we deobfuscate it we would find something like "anInt412" re-named/refactored is the same i think.
When you get a refactored client somebody has already figured out some of the "anInt" to what they really are and he renamed the field in every class to make it more understandable that its for example the modelId. Cause you cant be coding and remembering that "anInt145" the height was and "anInt447" the X coordinate thats why these get refactored.
This isn't just for integers same goes for methods etc.