Can you ask for your daughter to be moved to another classroom? If that is not possible, to another desk in the class so that she is physically separated from this other child by quite a distance, which I think the school should be able to do immediately. When my son was in a similar situation in K, I asked the teacher to move him to a desk where he could sit alone (the rest of the K kids sat at a large table together) and it helped my son get some peace during seat work - he was being hounded even during class work time because he was so "different" from others.
Another thing you could try would be to encourage your child to spend more time with other kids at recess, lunch etc - I know that it is impossible when the other child keeps following your child relentlessly. But, the other child loses their center stage when your daughter involves a few other children into their conversation and takes the focus off the child who compares herself to your child all the time. And, it helps to role-play with your chid how to go about it. It would involve specifics like - "Are there any friends in class that you would like to play with? What are their names? Why don't you try to either play or have a short conversation with Sue or Amy at lunch time today and see if they are interested in playing soccer with you? You can try asking Cara what book she is reading these days. etc."
We eventually moved our son to a school where he found a few peers to play with and to communicate with and where his abilities did not stand out so much.
