During mitosis, homologous chromosomes do not pair up during metaphase. Therefore the sister chromatids separate and form two new cells, with the same genetic information as the original cell. Remember the goal in mitosis is cell replication - therefore the cells at the end of mitosis are the same as the original cell.
The goal of meiosis is not cell replication. The purpose of meiosis is to produce germ cells or sex cells. Therefore the amount of genetic information is not the same as a body or somatic cell. During meiosis I, homologous chromosomes pair up during prophase 1 and crossing over happens. Then during meiosis 1 the homologous chromosomes split. It will not be until meiosis 2 that the sister chromatids separate, producing 4 cells that have half the amount of genetic information as the original cell and are genetically different from each other.