Do you have a source for your definitions?
http://en.wikipedia.org/wiki/Spree_killer
The definition of Serial Killer and Mass Murderer are in Wikepedia, and about every INTRODUCTION to CRIMINAL JUSTICE TEXTBOOK used in college. My textbooks ares stored now as I haven’t taught in several years, however those terms are what I said they were due to my criminal justice technology teaching experience.
Why didn’t you just look it up on the internet, or are you one of those who have to confront what you do not understand? You can google ‘mass murderer’ or ‘serial killer’...as for ‘spree killer’, that is a more recent term defining their behavior mostly.
A community college library will have used textbooks you can buy to familiarize yourself with those common terms.