The difference between fraternal and identical twins can be traced back on how they developed inside the womb of the mother by the time of conception. Fraternal twin is medically referred as dizygotic pregnancy. The prefix di- means two. Dizygotic means that the twin developed from two separate ova in the mother’s womb that were fertilized by two sperm of the father which bears different genetic characteristics. In other words, fraternal twins developed in the same womb but have different amniotic fluids and are having different characteristics because the ova and the sperm also bear different genetic make-up. That is the reason why fraternal twins does not look identical and are easily identified or recognized from the other. Fraternal twins often occur than identical twins. Fraternal twins can also be having different gender or same gender.
Identical twins, as the term implies refers to twins that are identical in nature, meaning, they almost have the same face and characteristics because of the fact that they developed from one ova and one sperm. Identical twins developed in a different way than that of the fraternal twins. Identical twins are monozygotic, meaning, they developed from one ova and one sperm, suggesting that they will naturally have the same characteristics with only a very slight variation. Identical twin occurs when the fertilized egg doubles its productions of cells thus resulting to two embryos in the same amniotic fluid. Thus the two embryos have the same chromosomes and DNA structures with slight differences as they continue to develop.