One of them is reinforcing, and the other is punishing.
Every time, and at the same time.
Now, when it comes to training with the e-collar, you are correct that we need to always be using it to reinforce.
Read this post by Darrin again.
Originally Posted by copterdocWhy does a dog flare the place that it was forced on back, or stopped with a whistle/nick?
Because it associates the aversive, with the location.
Aversive stimulus, always punishes something.
By conditioning the dog to go, stop, and come in response to that aversive, we assure that applying it as reinforcement, doesn't punish going, stopping, or coming.
But, it still punishes SOMETHING, when we apply an aversive to reinforce a behavior that we have conditioned to that aversive stimulus.
That's why it works as an indirect pressure correction for what the dog was doing wrong at the time that it was applied. And it's also why the dog can "blame" it on something that we didn't want the dog to blame it on.