Negligence is a two-part beast; criminal and civil negligence are different. Civil negligence is a topic that I will discuss in much more detail next week; criminal negligence is something I can dispose of rather quickly.
Again, most of the time that we talk about criminal negligence it's in the context of homicide, which hopefully none of you will ever have to worry about. Criminal negligence is basically "careless, inattentive, neglectful, willfully blind, or" in other words, really, really dumb. What's the difference between criminal negligence and recklessness? Really, not all that much; depends on how zealous the prosecutor wants to be.