Why do I always get compared to this girl?

So theres a girl at my school named mandy thats so pretty. People always just randomely say to me you and her should be best friends, you remind me of mandy, your style reminds me of mandy but your prettier than her, when i waled into a clroom some guy was like hey theres mandy and some other guy was like no thats not her. I think everything about hers better than me tho shes taller than me, shes outgoing and i am really shy, all the guys talk to her, shes a good dancer, and shes prettier than me why do i always get com[ared to her it bothers me