There is a difference between Life in Prison, and Life in Prison without the Possibility of Parole. Life without Parole is just that, until the end of the person's natural life. Regular Life in...
Felony offenses begin with a 1 year minimum and range upwards from that point depending on the wording of the statute/law that was passed by your state legislature.
There are many things that play a part in a murder case but the hardest is death penalty if they have that or life in prison. It depends on what country and state you are talking about.