Hot yoga was introduced by Bikram Choudhury, this style is practiced in a heated room, approximately 38-40 degrees F. This type of hota yoga allows the body to loosen tight muscles and sweat profusely, which is thought to be cleansing. This method incorporates a set series of 26 poses, not all yoga studios us them all.
Hatha is a very general term that includes many types of yoga. This type is usually slow paced and gentle and is a good class to join if you are a beginner.
This style is based on the teachings of the yogi B.K.S Iyengar, the focus is most concerned with bodily alignment. Iyengar yoga usually emphasizes holding poses over long periods versus moving quickly from one pose to the next like flow. Also, in Iyengar and in hot yoga classes, the instructor will use props such as blocks, straps and blankets.
The emphasis in Kundalini yoga is on the breath in conjunction with the physical postures and movement. The main purpose is freeing energy in the lower body and allowing it to move upwards. All poses or asanas practice controlling the breath, but in Kundalini, the exploration of the effects of the breath (also called prana, meaning energy) on the postures is essential. Kundalini uses rapid, repetitive movements rather than holding poses for a long time, and the teacher will often lead the class in chanting.
Vinyasa is also a general term that is used to describe many different types of classes. Vinyasa, which means movements with breath, these classes are more vigorous and usually involves a series of poses called Sun Salutations or a variation depending on the instructor. Class will start with a number of Sun Salutations to warm up the body for more intense poses like pigeon pose or cobra.
Pizer, A. (2009, July 6). Yoga style guide. About.com, Retrieved from http://yoga.about.com/od/typesofyoga/a/yogatypes.htm