How do you call to a "non similar" twins? I know there is a word to refer to the non similar twins.
There are identical twins and fraternal twins. The word you are looking for is fraternal.
Fraternal, nonidentical, or dizygotic twins occur from two different eggs, each fertilized by a different sperm. Therefore, fraternal twins have the same genetic resemblance as any pair of siblings (about half their genes in common).
(source: Steiner-Grossman, 1997)
The word you are looking for is Fraternal Twins