How are human embryonic stem cells and skin cells taken from the same person the same? How are they different? What causes the differences?

They are different because the embryonic stem cells can be all cell types of the body because they are Pluripotent. Where as the adult stem cells are thought to be limited to only their tissue of origin

Pluripotent (Adjective)

An immature stem cell, capable of giving rise to to several different types of cell.