I think that Harsh discipline does equal abuse. I think that it is awful to punish someone in that way unless you are talking about someone in prison who may deserve it for killing someone else. Harsh is harsh there is no other way to play that kind of dicipline down.
I believe harsh discipline does equal abuse. Of course we are going to have a lot of gray area between what qualifies as abuse and what qualifies as a just punishment. This issue is not black and white with a clear and defined line that breaks the two sides. There is a large subjective area where people are bound to disagree.
There is a line that shouldn't be crossed when it comes to discipline. Physical discipline has been used for generations without it being physical abuse. The determination is how far the person in control goes. If physical punishment is chosen to be the path that a parent is going to use to steer their kids, it needs to never cross the line and become physical abuse. A spank here or there is fine. Bruising your kid so they can't walk or sit down is not.
Harsh discipline has it's place in parenting. If a parent catches their child acting beyond the normal scale of misbehaving it may be beneficial to put an immediate stop to that activity with harsh discipline. If the parent takes to the harsh discipline too often or takes enjoyment in the discipline then that method should be abandoned. Having a severe punishment that's only used once or twice a childhood gives the child a chance to respect that method of discipline. They know if they step too far out of line there are serious concequenses far beyond what they typically recieve.