The "Standing Posterior Deltoid Stretch" primarily targets the Posterior Deltoid (back of the shoulders) and is a very difficult stretch to feel depending on your anatomy.  The key to the stretch is to pull the arm to the side, and upwards to effectively stretch the back of the shoulders.  To add an extra stretch, pull the arm away and upwards and let the shoulder blade glide apart (oppose to keeping them together).

The "Standing Lateral Deltoid Stretch" primary targets the Lateral Deltoid (side of the shoulders) and can be a difficult stretch to feel depending on your bone structure/anatomy.  The key to this stretch is to use the opposite arm to pull the stretching arm away from the body for a more effective stretch.

The "Standing Anterior Deltoid Stretch" primary stretches the Anterior Deltoid (front shoulders) and Upper Chest (Pectoralis Major - Clavicular) along with the Biceps.  This stretch is great for workout programs that have intense chest/shoulder days, or any high-intensity pushing programs.  The stretch can be altered for a deeper stretch by bending the elbows and placing hands on a stationary object for support, and squatting into a deeper stretch.

The "Seated Anterior Deltoid Stretch" primary stretches the Anterior Deltoid (front shoulder), along with the Bicep Brachii (front of the upper arm).  This is an excellent stretch if you feel tightness in the front of the shoulders, or biceps - it should be performed on a mat, not on the floor (may cause you to slip).