Similarity between homozygous and heterozygous

If you are speaking of genetics, the only real similarity between the two is that they are terms used to describe alleles that are found on a particular gene. If you have homozygous alleles, then both of them are the same. If you have heterozygous alleles, then the two of them are different. In the case of sex chromosomes, females are homozygous, having XX while males are heterozygous, having XY.