To get the benefits of Pilates, you need to actually be doing Pilates. Unfortunately, many studios today use equipment like TRX, barre, and bosu, which though they might be fun to workout on, are not equipment designed by Joseph Pilates.
Mat and reformer have an order. Joseph Pilates had an order to mat and reformer in order to properly warm up the body to prepare it for the next exercise.
Classical Pilates utilizes all the apparatus. The various apparatus are designed to lengthen, lift, open, strengthen, and stretch the body so you can better perform the mat and reformer work as well as your everyday activities.
Classical Pilates instructors go through rigorous training. Through training and 600+ hours of apprenticeship they learn which exercise on which apparatus is right for you so you can progress and get stronger.