The difference? One you're shaving when it's the dark, the other... in all seriousness though, there is no difference. Some folk prefer night, others morning. I favour morning personally so I can enjoy a close shave throughout the day
Bill Cosby to Ray Charles: "Why are you shaving with the lights out, Ray? You're going to cut yourself."
Ray Charles: "Man, I been shavin' in the dark all my life."