If there are no differences between the amino acid sequences in the cytochrome c protein of humans and chimpanzees, why aren't we the same species?

The two factors that determine the shape of a protein 
1.  Primary structure. The sequence of amino acids. Amino acids are the building blocks of protein. It is a strong of linearity that can be thousands in length. Moreover, the formation of the amino acid and its system is influenced by its genes’ nucleotides arrangement.   
2. Hence the next factor is how is the structure of the amino acids bended and folded with itself that forms the certain protein molecule and forms the larger complex structure

Gravitational force i believe