Why does my older sister compete with me in everything?

There is always competition between sisters, but most often it is the youngest sister competing with the older sister. However, in many cases (I'm not saying this is yours) the youngest sister usually gets doted on more by parents or gets away with a lot more. Maybe your sister just wants to be noticed a bit more. Don't get angry or shout. Just tell her how you feel, and how you want to be independent and not have people like your sister copy you. Also, you are obviously slightly more confident looks and personality wise than your sister, so again it could be an attention thing. If she doesn't listen when you talk to her, talk to your parents.