Here's a taste of a delightful interview from the India Times, with Swami Niranjanananda Saraswati -

What is the difference between Yoga and Tantra?

Tantra says you have to accept yourself as you are – do not restrain, just accept, but be aware and you will transcend.’ Yoga promotes restraint. Both ways are acceptable. Tantra and Yoga may be two different manifestations but their genesis is the same. All concepts of Yoga are derived from Tantra.

Tantra talks of the union of Shiva and Shakti. Shakti has nearly always been defined as kundalini, and Shiva, the male aspect, has been defined as chetana or consciousness. Tantra is not really referring to a physical relationship. It says that in order to experience internal union you first experience external union; to experience internal bliss, experience external bliss. The difference is external bliss is momentary; internal bliss is continuous.

In Tantra there are initiations which are awakening of Shakti. The practice of asana is an initiation for the body. Pranayama is initiation of the pranas. The only difference between Tantra and Yoga is that Yoga is outgoing; it deals more with the world, body, mind, personality, emotions, actions and environment, whereas Tantra is more meditative.

You require desire because, for the evolution of consciousness, conflict is necessary. It is a means for awakening part of the consciousness. If there were no conflicts, there would be no evolution. There would be a stagnant state of consciousness.

How should we deal with desires?

We must accept them. If i desire to slap you, i should think of the repercussions it can have, positive or negative. If i simply follow my emotions there will be a big fight between us. This is where you have to learn to detach yourself. Both processes happen together. You allow emotions to flourish, observe them, and learn how to control them. You come to know when it is the right time for action and let that energy manifest. Then this manifestation will be positive and creative, rather than haphazard. You wait for the right time, you follow that desire through, so there is no conflict.


More: http://timesofindia.indiatimes.com/home/opinion/speaking-tree/Use-your-desires-to-evolve-consciously/