This question is asked by many juniors and adults alike. Chipping is where the ball is located just off the putting surface in either the first or second cut of grass. The ball travels with minimum air time and maximum ground time towards the hole. Pitching is where the ball is a bit further back from the 2nd cut around the green and the ball travels with more air time and less ground time to reach the hole.
Chipping 7 iron - SW depending on the distance of the shot. The further the distance the less lofted club is to be used.
Pitching
The chipping motion requires very little back swing and forward swing. The key factor in the motion is that the sternum which is the swing center must move towards the target after impact. See below a chipping drill where the back foot is up on its toe forcing the weight on the forward foot with hands and sternum in front of the ball which is placed originally in the center in the setup. Your target is the first circle with the roll out to the second circle. This motion is equal tempo back and through. Notice the back of the left hand of the student through impact and finishes flat and NOT cupped. This allows for the clubface to be square at impact and helps control the air time.