Classical conditioning (do you hear the music of Rimsky Korsakov) is kown as S-S learning. The organism learns to associate a conditioned stimulus (CS) with an unconditioned stimulus (UCS) through a number of pairing usually contiguous in time, although it can be contiguous in space. The UCS evokes the unconditioned response (UCR) naturally. By pairing the CS with the UCS and then the UCS with the UCR, eventually the organism begins to show a partial part of the UCS when the CS is presented, which becomes the conditioned response (CR). Thus, the dog hears a buzzer (CS) when one door is open and that starts the saliva flowing CR before the UCS (food) is presented causing the UCR. (more saliva). Eventually, the CS elicits the CR without presentation of the UCS. If this is done often enough without presentation of the UCS, the response would be extinguished.
Operant conditioning is S-R learning. An organism befores a behavior to some stimulus (S) and if it responds to the correct S, it gets reinforced R. If it is positively reinforced, the chances it will perform the same response to the same stimulus will increase in probability. If it is punished, it will become less likely to respond that way to that stimulus. If a rat learns that if he turns right he will find food, but if he turns left he won't, he will soon learn to RUN, not amble, to the right. A right hand turn is considered a S+. If he learns that if he turns right, he will cower and not go down the maze unless forced. Punishment is often learned after one trial and produces "anxiety". If you teach the rat that turning to the right gets food, then stop feeding him, but will feed him to turn left, he gets NEGATVELY REINFORCED for turning right (S-) and positively reinforced for turning left (S+). You can also extinguish responses.