Kundalini yoga is a very ancient form of yoga which has gained popularity in west just recently. Although this form of yoga was not taught to common public before, its founder believed that everyone should get the benefits of this form of yoga.
Kundalini is basically the untapped energy based at the base of the spine which can be brought up through body awakening each of the seven chakras. When this energy reaches the crown chakra full enlightenment occurs. Kundalini energy is often represented in the form of a snake that is coiled at the base of your spine. Each pose in Kundalini yoga is in conjunction with specific breathing pattern which help to intensify the effect of the pose and draws the energy upwards setting the lower body free. The movements in Kundalini yoga may involve rapid sequences of repetitive movements with breathing in a particular way or holding a pose in particular position and breathing in a particular way. A Kundalini class will normally consist of a warm-up session followed by poses that stretch the spine and improves flexibility. It will also include some chanting and meditation session involving certain mantras, pranayama and mudras. The devotees of Kundalini often wear a white flowing robe and head wraps. Kundalini yoga is one of the most spiritual types of yoga that pays a lot of emphasis on breathing, meditation and chanting. It often goes beyond the physical performance of poses but many of its sequences are also very physically intense. If you are ready for both mental and physical challenge in a yoga session then Kundalini yoga can be an ideal choice.

Hatha yoga is a term that can be used interchangeably with the term yoga. So when you do ashtanga yoga then you are doing hatha yoga or if you do Iyengar yoga then too you are doing hatha yoga. Thus it can be said that hatha yoga may describe any of the physical practices of yoga. Hatha yoga is a good way to learn the basics of yoga and get comfortable with this form of exercise. You will learn many relaxation techniques and basic poses of yoga in a hatha yoga session. A hatha yoga class will involve slow paced stretching exercises along with some breathing exercises. Many people find this form of yoga very meditative and slow, while some love the relax feeling it gives after a session.