"Constant" means happening often. So if you were at work and every single hour, somebody stopped by your desk and asked you for a favor, that would be constant. "Consistent" means in a manner that can be almost predicted. As an example: If you were at work and every week on Thursday you grabbed lunch with your friend, that would be consistent. It's consistent because it's always the same day and time. Since it's only once a week, it's only consistent, but not constant. Hope that helps.

Actually, there is a difference. Something is constant if it does not stop, though it may vary. Consistent things may start and stop, but do not vary. Someone has consistent behavior, but but a results of a physics experiment are constant.