The World And Living Beings

Theres 10 worlds in Universe（十法界） :

1. 6 Worlds of Reincarnation Realm （六道轮回）

a.       Hell （地狱道）

b.      Hungry ghost （饿鬼道）

c.       Asura  （阿修罗道）

d.      Animal （畜牲道）

e.      Human（人道）

f.        Deva （天道）

  2. 4 Worlds of Saints （四圣法界）

a.       Arahant （阿罗汉）

b.      Pachekka Buddha （僻支佛）

c.       Boddhisattva（菩萨）

d.      Buddha （佛）

The world of rebirth living being is still lives in samsara circle of live of those 6 realms, and should pay bad karma from the past life. In Sutra of The Great Vows of Ksitigarbha Bodhisattva (地藏菩薩本願經)

tell us that a human after died if they go to hell as demon, they will be punished in hell until finish their bad karma in hell, after that they can live as animal (from small form to big form) until their bad karma as animal finish, after that they can be a human again.

If a human become a deva, they live in heaven and they live very happy and has very long age. But when they shirt become not good looking and stinky, that’s mean their age will finish as deva, then they can be born as animal or human again.

But the second world is already didn’t need to rebirth to pay their karma, because all Saint can be neutralize their own karma. Forever they never could be born as rebirth living being anymore.

Arahant or Sravaka (the Hearers) is the disciples of the Buddha who understand the Four Noble Truths, rid themselves of the unreality of the phenomenal, and enter nirvana.

Pachekka Buddha (the Conditionally Awakened Ones) is also known as Solitary Realizers, those who are enlightened through reasoning on the riddle of life, especially as defined in the twelve nidanas (the twelve links in the chain od existence).

Buddha is “The Fully Enlightened One” or “The Awakened One”. It is the title given to those who have attained supreme and perfect Enlightenment. And their age is counts by kalpas and they wouldn't come back to reincarnation anymore. Boddhisattva is 1 level below The Buddha, They soon will get enlightenment to become a Buddha.

Kalpa is A long period of time; an age. 1 small kalpa = 16.8 million years; 1 medium kalpa = 336 million years; 1 great kalpa = 1.344 billion years.