Electric massagers are used more diversely and offer a wide range of benefits in different areas. Muscle electrostimulators or TENS units, on the other hand, are used for transcutaneous nerve stimulation and focus on pain control by creating more strength and endurance in muscle groups. So no, they are not the same.
Masseurs are used in the sports world to enhance the performance of athletes during training and competition. They activate the muscles, improve blood circulation and promote the growth of muscle mass.