Which art in heaven = a sense of distance.
When there is two possibilities to reading a passage in scripture or there are two different renditions of the same passage then God means both to be true.
He also intends a sense of distance not to be there. There is a contradiction but it is on purpose rom 15:4
So both closeness and distance are intended. God is holy, which means He is separate and set apart. Which art in heaven is the Rabbinic way of maintaining the holiness of God.
Genesis 1:1 In the beginning God created the heaven and the earth.
Deuteronomy 4:39 Know therefore this day, and consider it in thine heart, that the LORD he is God in heaven above, and upon the earth beneath: there is none else.