She is prettier, smarter, more popular, and many other things. I do have a somewhat better personality than her, but who cares about that, it's not the first thing you notice on someone.

She's not smarter than you, and you shouldn't tell yourself that. There's something is psychology called the 'self fulfilling prophecy' which is the concept that a person's thoughts influence reality. You tell yourself that you aren't smart and your brain sort of surrenders before it really gives 100% to anything that requires a lot of brainpower. People have different talents, and they are all valuable. You should start considering yourself your sister's equal and love her for who she is, and love yourself. The same is true with your personality and your looks. you should stop telling yourself that you aren't as pretty as your sister, and and you should stop telling yourself that your personality is better. Always look for ways to improve yourself and be positive to both yourself and your sister.

You sound young, and that's fine. Just please remember to be kind to yourself and your sister.