According to Yogapedia, Ha means sun and tha means moon in sanskrit. Hatha is is designed to join or "yoke" together these opposing energies through physical postures, (asanas), and breathing techniques, (pranayama). The purpose of Hatha Yoga practice is to calm your body, mind and spirit and bring your whole self into balance.
Yin yoga is a gentler practice that harnesses cooler lunar and feminine energies. It is the perfect practice to balance our "yang", or very busy and overstressed lifestyles. This practice shifts the focus out of the muscles and into the deeper tissues of the body. In holding the mostly seated postures for a sustained amount of time, it benefits the joints, fascia, bones, ligaments tendons, and connective tissue. It is also a more meditative practice.
This practice involves the use of props to support you as "rest" in simple poses for a length of time. This practice deeply benefits the Central Nervous System, by shifting you out if the Sympathetic Nervous System, ( fight or flight mode), into the Parasympathetic Nervous System, ( rest and digest mode ). It can also be a meditative practice.
Also known as "yogic sleep", this practice draws the attention inward through a series of techniques including deep relaxation, rotation of consciousness and guided visualization that ultimately leads to the state of Yoga Nidra.While the practitioner may appear to be sleep they are in a deeply restful state, while remaining awake. The benefits of this practice include stress reduction, which ultimately resets the Central Nervous System and endocrine systems. It gives the body the opportunity to completely relax and rejuvenate.