What is the difference between sister chromatids and homologous pairs?

The difference between homologous pairs and sister chromatids is that homologous pairs are already in the cell to begin with, but sister chromatids are formed during the meiosis I stage The purpose of meiosis is to drop the number of chromosomes in a cell down to 23 so that when a sperm and egg combine, 46 chromosomes are present.

Homologous pairs are chromosome pairs, where one chromosome comes from the mother and the other comes from the father. They are present in diploid cells and are not identical, only similar. Sister chromatids are identical and are formed from the homologous pairs in meiosis I and separate in the meiosis II stage.