Supercropping = the act of pinching stems in order to cause them to strengthen.
This helps to control height and also allows the plant to support heavier flowers.

LST (Low-stress training) = the act of bending stems and branches & tying them down in order to train them to grow in a direction other than straight up.
Bending the main stem over will cause the side branching to grow more vigorously, due to the increased light they will receive but also due to the redistribution of plant hormones called Auxins.

You can start to do them both fairly early in the plant's life... I've started pinchng and bending as early as 2 weeks.

Both are great methods of manipulating your plants... I'm a firm believer in both!