To make it simple:
Positive reinforcement “something good is added”
And with
Negative reinforcement “something” unpleasant is removed
But both methods aim to increase the likelihood of behaviour to be repeated.
But positive reinforcement training uses “rewards” and negative reinforcement training uses “relief”
For example:
Let’s add a primary reinforcer to teaching a dog to follow or to sit or to down.
The dog is much more comfortable and willing to work for what is genetically driven
We all need food to survive
Using positive reinforcement as a motivator keeps the dog happy and the process of learning is quicker and easier
Let’s add a negative reinforcement to teach the dog to sit, or down
The dog is avoiding the pressure of the leash on his neck and is following his instinct to avoid or flee the circumstance – so the behaviour is offered but in an negative state of mind
Which makes the process of learning more difficult and slower