Whats the difference between double homicide and abortion?

Many states states consider the death of a unborn fetus as a result of a crime a homicide. In most instances the fetus only has to be between inception to 7 weeks in development. What difference does it make if the fetus is killed in a criminal situation or by a surgeon? The fetus at inception to 7 weeks is dead either way. Why does there appear to be a double standard concerning the governments interpretation of "life" and to the extent that life of the fetus should be protected?