I don't understand how people cannot see a difference in these cases. Michael Vick essentially lead a crime ring for multiple years. Dog fights and selling guns and drugs were all part of his "kennel". When the crimes were discovered he denied any wrongdoing and tried to cover up any evidence of what was going on.
Stallworth drank too much, drove an killed someone. He called 911 and reported what had happened immediately. The family of the victim asked the court and the DA for leniency as they were willing to take a cash settlement in lieu of sending Stallworth to prison.
Saying "Vick killed dogs and got 2 years and Stallworth killed a person and got 30 days" is a VAST simplification of what occurred.