What is cloning?
Artificial embryo twinning imitates the natural process that occurs when a fertilised egg separates into two embryos that develop into identical twins. In artificial embryo twinning, scientists manually separate a very early embryo into two cells and allow them to develop separately. The embryos are then placed into a surrogate mother and delivered. Since the embryos came from the same 'parent' embryo, they are genetically identical.
In somatic cell nuclear transfer, scientists isolate a somatic cell (any cell other then sperm or eggs) from an organism and remove the nucleus. Next, they insert the nucleus into an unfertilised egg cell with its nucleus removed. This egg cell now contains two complete sets of chromosones from the original somatic cell, and therefore develops into an embryo that is genetically identical to the original organism.