What is the difference between Homozygous dominant and recessive genes?

First, it is important to know what homozygous means. Homozygous means that in an organism, both copies of a given gene have the same allele. A homozygous dominant is when an organism carries two copies of the same dominant allele. Only a single copy of a dominant allele is required for it to manifest in an individual. Homozygous recessive is when an organism carries two copies of the same recessive allele.

For a recessive gene, an organism needs to have two copies of the same recessive alleles for it to manifest in an individual. Heterozygous means that an organism has two different alleles of a gene. This is the opposite of homozygous. Heterozygous dominant would still manifest in an individual, but heterozygous recessive will not manifest in an individual.