Although the AT is often referred to alongside both Yoga and Pilates, they are not the same. Pilates is an exercise system and Yoga involves a series of postures.
The Alexander Technique, on the other hand, although also a physical method, is primarily a technique for improving awareness of how we use our bodies in any activity. You can apply the principles of the Alexander Technique to doing exercises such as Pilates or to practicing Yoga, but you cannot apply Pilates to how you practise the Alexander Technique.