Yama vs. Niyama — What's the Difference?

Yama or Yamarāja is a Hindu and Buddhist deity of death, dharma, the south direction, and the underworld, belonging to an early stratum of Rigvedic Hindu deities. In Sanskrit, his name can be interpreted to mean "twin".

The Niyamas (Sanskrit: नियम) are positive duties or observances. In Indian traditions, particularly Yoga, niyamas and their complement, Yamas, are recommended activities and habits for healthy living, spiritual enlightenment, and a liberated state of existence.

The king of the infernal regions, corresponding to the Greek Pluto, and also the judge of departed souls. In later times he is more exclusively considered the dire judge of all, and the tormentor of the wicked. He is represented as of a green color, with red garments, having a crown on his head, his eyes inflamed, and sitting on a buffalo, with a club and noose in his hands.

Hindu god of death and lord of the underworld