Vishwa Yoga is a form of Tantric Yoga, for discovering and cultivating the purpose, power, and prosperity in all aspect of life. Vishwa is a Sanskrit name, it means the 'whole world'. Thus, Vishwa Yoga means - Yoga for the whole world. However, in Indian scriptures, 'Vishwa' is one of the names of Vishnu as well as Shiva. Thus the name carries the auspiciousness.
Yoga is an ancient philosophy, practice, and state of the being. There are many approaches to yoga. Chances are, the Yoga you and everyone else you know who is into yoga, have been practicing some style of Hatha yoga. In fact, any type of yoga that includes bodily postures and/or breathing techniques is Hatha Yoga.
The word Hatha in Sanskrit literally means force or power, implying a practice requiring work on your part which is intended to liberate the dormant energies inside you. Also, the word Hatha is a combination of two separate "bija mantras" or single syllables. "Ha" represents the vital life force, pranic energy or sun/stimulating energy, "tha" represents mind, mental or moon/calming energy according to the Hatha Yoga Pradipika, one of the oldest and primary texts on Hatha Yoga. Yogis also translate "Ha" as the masculine or solar energy and "tha" as the feminine or lunar energy. Regardless, the point is that through this practice we bring balance to two opposing forces.
Most Yoga classes focus on asana or physical posture. Some with a strong emphasis on physical alignment to keep your body safe and injury free. Others focus on flowing from one asana to another to build stamina, strength, and heat. While others have a more mellow approach to restore the practitioner and reduce the wear and tear of life on the body. All these are great approaches and need to be practiced at some point, but a Yoga class with Tantric approach will have a slightly different approach.
Tantra & Tantric Yoga
The word Tantra (Tantric is an adjective which describes something coming from Tantra) is made up of two words: Tanoti and Trayati. Tanoti means "to weave, to expand, to stretch, to extend", while the word Trayati means "to liberate or free". Therefore Tantra (tan+tra) means to expand one's experience and awareness of everything, to extend the frontiers of apprehension beyond the material, and hence to attain spiritual knowledge and liberation. A tantric text called the 'Varahi Tantra' provides more than two dozen subjects of Tantra, such as Consciousness, Spiritual practices, Yoga, Medicine, Science, use of Sexual energy as a means of higher awareness and much more. Tantra is a master ancient tradition, a system intended to teach us how to live life with fullest. Yoga is the practical application of Tantra.
So in a Tantric Yoga, using Asana as a foundation, you will seamlessly weave the deeper practices of Pranayama, Mudra, Bandha, Mantra, Kriya, and Meditation. There will be a little guidance on alignment and some 'Vinyasa' (flowing from one asana to the other) and even some restorative/supported work. As you will experience that it won't stop with the physical body. Through specialized breathing and meditation techniques, builds this "sensitivity to the more subtle forces" which is called prana or vital life force. The ancient Hatha Yogis believed through learning to control prana, one also learns to control the mind. You will leave a Tantric Yoga class feeling like you've cultivated vital life force and a clear mind.