The use of electric massagers is more varied, with a wide range of benefits in different areas. In contrast, electro muscle stimulators or TENS equipment are used for transcutaneous nerve stimulation and focus on pain control, generating greater strength and endurance in muscle groups. So no, they are not the same.
Massagers are used in the sports world, to increase the performance of athletes in training and competitions. They activate the musculature, improve vascularisation and promote the growth of muscle mass.