The provisional teachings preceding the Lotus Sutra expounded that the 10 Worlds refer to 10 distinct & separate realms. In other words, the 10 Worlds were perceived as distinct states of life separated from 1 another.
It was Lotus Sutra that transformed this concept by revealing that the 10 Worlds are in fact life-conditions inherent in the life of a single individual . This principle is called the mutual possession of the 10 Worlds.
The 10 are the world of hell, hungry spirits, animals, asuras, human beings, heavenly beings, voice hearers, cause-awakened ones, bodhisattva & Buddhahood. The 1st 6 states - the world of hell, hungry spirits, animals, asuras, human beings & heavenly beings - are collectively called the 6 Paths. The life states of voice hearers, cause-awakened ones, bodhisattva & Buddhahood are collectively named the 4 Noble Worlds.
In regard to the 6 Paths, the Daishonin states: "When we look from time to time at a person's face, we find him or her sometimes joyful, sometimes enraged, & sometimes calm. At time greed appears in the person's face, at times foolishness, & at times perversity. Rage is the world of Hell, greed is that of hungry spirits, foolishness is that of animals, perversity is that of asuras, joy is that of heaven, & calmness is that of human beings."
The 6 Paths & the 10 Worlds as life states or life-conditions are inherent in each of us.
The world of heavenly beings
The world of heavenly beings is also called the world of heaven. In India, this world originally referred to the realm where heavenly beings (supernatural beings like gods & deities) reside in. It was a belief then that those who conducted good deeds in this lifetime will be reborn in this realm in their next existence.
Buddhism views the world of heavenly beings as a life state of joy which 1 experience when 1's desire is fulfilled. The Daishonin says, "Joy is that of heaven".
The world of heavenly beings describes a life-condition immersed in joy when 1's instinctive, materialistic, social or spiritual desires are fulfilled.
However, 1 must not be too captivated by this world & be self-contented with it. The reason is that the joy experienced in the world of heaven is temporary. In addition, when 1 reaches the peak of this joy, 1 will inevitably encounter the Devil of the Sixth Heaven, a function that seeks to ruin 1's life by making use of 1's weaknesses.
Furthermore, the world of heaven cannot provide a fundamental solution to the 4 universal sufferings of birth, old age, sickness & death. Though 1 may experience joy, he doesn't have the wisdom to be awakened to the fundamental Law of life. Therefore, those who are in the world of heaven are unable to find the basic solution to the sufferings in life.