Topping is the process of removing the growing top from the plant, some pinch it off.. i cut it off..

you can see the difference between a topped and a non topped plant roughly the same size and same age.. sex still.. unknown...

Topping encourages the branches to grow larger, creating many medium sized colas as opposed to one large and many smallish/medium sized colas.

LST on the other hand.. is the art of bending the stem to encourage branche growth, and you get to keep the main cola.. which from what i understand, is the best part