What is the difference between Yama …

Yama means restraints or abstention. Yamas are practices to eliminate wrong, harmful or disturbing behaviour. They create a foundation of right living. Yama consists of five moral codes of conduct. These are :
(i) Ahimsa or non-violence : It means not to hurt any creature mentally or physically through mind, speech or action. We must not display any negative emotions or injure anyone.
(ii) Satya or truthfulness : It is a presentation of a matter with truthfulness in thought, word and deed. We must not tell a lie in all the dealings of life.
(iii) Asteya or Non-stealing : of anything in life such as money, material, ideas, speeches or writings. We should feel satisfied, whatever God has given us.
(iv) Celibacy or Brahmacharya : It means refraining from all the activities related to sexual enjoyment directly or indirectly.
(v) Aparigraha or non-possessiveness : It means to lead a life with minimum requirements.

Niyama  literally means positive duties or observances. In Indian traditions, particularly Yoga, niyamas and its complement, Yamas, are recommended activities and habits for healthy living, spiritual enlightenment and liberated state of existence.