Death is death, be it murder or natural causes, someone is dead so why do people try to quantify it?

In a recent thread about the death penalty some spoke of using on those that killed children, or during rape/murder crimes, etc. Why, if a person murders a 5 year old, a 15 year old, a 50 year old, the victim is still dead? Why do people want think that murdering a 5 year old is any worse than murdering a 50 year old, at the end of the day, there is a dead body? Are people putting value on life (more than they already are), where certain lives have more value than others? Are the families of the murdered older folk going to say they have less to cry about because grandpa got smoked in a robbery; they have it better than the child killed because the kidnapper got scared?