It always kind of cracks me up when I hear someone having to explain the difference between between these 2 breeds of VM.

At one point back in school a friend said to me "hey, I can't figure out how to install and boot JVM on Virtual Box. I need to use it for homework in another class. Help me?"

I wish I had been able to explain it as succinctly as you. Instead I sat there laughing in the guy's face for a good minute, eventually realizing from his expression that he was being serious, which only made me laugh even harder.