Why does this girl I work with keep comparing herself to me?

Anonymous
So there is this girl who I work with and I’m now in a friendship group with her and a few other girls. The first time I met her, she said ‘no offence, but you kind of sound like you are from private school’ and said ‘if I could imagine what it would be like to go to private school, I would imagine people who looked like you’
On a separate occasion she said ‘you are so elegant and sophisticated and I’m like a pig’

She keeps mentioning this to me all the time too, that I look dress and act like a royal. She said to me ‘I wish I could be like you and carry myself the way you carry yourself, it’s doing my head in.’ And she also said ‘I wish I was like you and looked nice all the time and fresh faced’

Then other times she will insult me and put me down. She is always trying to compete with me and says ‘I like your necklace but mine is really expensive and it’s the only expensive thing I own’
Then when we are working together she constantly asks me how much work I am getting done
On a separate occasion she was staring at me and I asked her why she was staring and she said ‘I wish I was you.’ One time I was wearing a short blue skater dress and she said ‘you have long ballerina legs I’m so jealous’

The other day out of no where she hit me on the back and I told her not to and it hurt and she said ‘good’ in a serious way.

Why does she keep comparing myself to her and competing with me?
Why does this girl I work with keep comparing herself to me?
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