The difference between regular sex and Tantra is awareness. One of the fundamental parts of the ecstasy you feel during sacred sex comes from the spiritual connection between you and your love partner. It is difficult to stay aware of your spiritual connection when your sex center gets very turned on unless you have trained how to do so.
Staying aware when you are very turned on physically is challenging, but incredibly rewarding. When you learn to stay aware of all that you are during the moments of highest excitement , you are in a Tantic state, a state of union between the male and female energy, between the body, the mind and the spirit, and the emotions flow freely and unencumbered like a river between the different levels.
It is a state of pleasure and deep enjoyment, a celebration of being fully alive in the NOW. When you are in this state, time stays still, and your experience of bliss is stretched and intense. The now is eternal. That is why the experience that Tantric love brings is always fresh and new.