The main difference between a chador and a burka is that a burka covers the face, whereas a chador wraps around and covers the head and hair, but leaves the face exposed. Both are worn by Iranian and Islamic women as body-covers.
The burka is the most concealing cover worn by Islamic women. Some burkas cover the eyes with a veil, while others leave the eyes exposed.
The chador is an outer garment that is worn in public places. It is a semi-circle of fabric and is held together in the front. Another headscarf is typically worn underneath.
Covering oneself while in public is seen as modest expression of a woman's religious faith.