I am always surprised when I am listening to the radio how often people mix up assault with battery. In my torts class, we studied assault and battery by the elements. We had the elements drilled into us, to the extent that one of the torts teachers said we should be able to wake up in the middle of the night and recite the elements from memory. I can just imagine sleeping peacefully, and suddenly, my eyes popping open. I would sit up in bed and, in a zombie-like haze, start announcing:
3) imminent apprehension of the harm or offence
4) the harm or offence
2) intent to touch
3) intent to harm or offend
4) the harm or offense
The elements look the same, right? Well, the difference is that assault is just the apprehension of a harm or offence, so it doesn't require contact. Battery usually involves contact while assault only involves thinking you will get hurt. It's the difference between someone faking a punch (assault) and actually punching someone (battery).
Of course, you don't have to take my word for it. Any good lawyer would say it depends on the circumstances. And of course, when you are a law student, you get to say that anything you do or say should not be construed as legal advice.
So there you have it: the difference between assault and battery.