Durga is Kali and Kali is Durga. Although worshipped in the two different from, both Durga and Kali are representations of the same feminine ‘Shakti’. According to Hindu mythology, Goddess Shakti or the feminine power was created by the culmination of energies of all the Gods. The birth of Maa Durga was mainly to destroy the tyranny caused by the Kind of Asuras (demons Mahisasura. The slaying of Mahisasura symbolizes the victory of good over evil.
Goddess Kali originated from the forehead or brow of Maa Durga in order to kill the demons Shimbhu and Nishumbhu. Legend has it that Maa Kali became so involved in the battle with the demons and the bloodshed surrounding it that she lot all control and started destroying everything in her path. The killing only stopped when Lord Shiva threw himself under her feet.
Therefore a popular image of Kali shows her with one foot on the chest of Lord Shiva with her tongue handing out, as if in astonishment or regret. Because Goddess Kali is mainly associated with destruction of evil, her image often shows her as being dark and ferocious with a garland made of demon-heads around her neck. Goddess Kali represents destruction and is intended to help devotees come to terms with the cycle of birth and death.
Maa Kali is depicted in two different forms – having four arms or ten arms. In both the forms Kali Maa is shown to be black in color, her eyes red with intoxication and rage. She is often seen wearing a garland of human heads. The four-armed image of Goddess kali sis also shown holding a cup made of human skull, a sword, a trident (trishul) and a severed head.
In the image with ten arms, Goddess Kali, also known as Mahakali is depicted with ten heads and legs as well. In each of her hands she holds a weapon, given to her by each God.
The images of Goddesses Durga and Kali also depict the win of good over evil. Goddess Durga is depicted sitting on a lion or tiger and standing over the defeated body of Mahisasura, the demon, thus depicting the fall of ego, anger, greed and all other vices in this world.
During Durga Puja, all the forms of Goddess Durga are worshipped. The worship of Goddess Kali coincides with Diwali, the Festival of lights. This day falls in the Hindu month of Kartik (October/November) after Durga Puja. In Bengal, lamps are lighted in honor of Goddess Kali. Since Goddess kali is feared by all, people devote a lot of attention in worshipping her and fro protection against all evils.