Vedokt Aayurdayam : It is defined by Ved. It is said to be 1000 years.
Poorn or Graha Aayurdayam :   It is one cycle of all Graha Dashaa in one's horoscope - that is 12o years, but some bad Graha may cause death. 120 is obtained by adding the full length of major periods (Dashaa) of all the nine planets including Raahu and Ketu (Sun 6 years + Moon 10 years + Mars 7 years + Rahu 18 years + Guru 16 years + Shani 19 years + Budh 17 years + Ketu 7years + Sukra 20 years = 120 years total).
Sudden Death or Apa mrityu or Durmaranam : Its by some Shaap or Yam Gand,.. This can happen anytime to anybody.

Death may be classified in day to day speaking terms also. There are two main types Poorn Aayu and Akaal Mrityu. Akaal Mrityu is again subdivided in two - Javaan Mrityu and Baal Mrityu. Durghatanaa Mrityu may happen to anybody.

Poorn Aayu or Full Age :  When a person dies after the age of 80-85 naturally or after a brief illness, it is called Poorn Aayu
Durghatanaa or Accidental Death : When a person dies in an accident or by burning in fire, it is called Durghatanaa Mrityu
Javaan Mrityu or Young Death : When a man dies between 16 to 55 or 60 it is called Javaan Mrityu
Baal Mrityu : If a child dies before the age of 16 or so it is called as Baal Mrityu.

--The Garud Puraan states that those who have spent several years in the dreadful hell and have no descendents to perform Shraaddh (prescribed rites) in their favor become messengers of Yam Raaj, god of death.
--The Garud Puraan holds, "if one chants the holy name of the Lord, even in a helpless condition or without desiring to do so, all the reactions of his sinful life are nullified."
--The Skand Puraan declares, by chanting once the the two-syllabled name of the Lord, Hari, one makes sure of his path to Moksh.
--The Padm Puraan states that one who is cremated with Tulasee twigs for firewood would attain a permanent place in Vishnu Lok. It is said that even great sinners would be absolved of their sins if their dead bodies are cremated with Tulasee Twigs. Even a peace of Tulasee twig at the bottom of the funeral pyre is stated to grant Moksh even to a hardcore sinner. A small piece of Tulasee twig has the power of purifying the firewood in the pyre in the same way the water of river Ganges purifies all waters mixed with it. It is also said that servants of Yam Raj keeps away from one whose body is cremated with Tulasee twigs.