There are ten hindrances to enlightenment (shown below) and four stages of realization (enlightenment) based on how many hindrances have been eliminated and / or the degree to which they have been eliminated.
A Buddha is someone who is fully enlightened. A person who is fully enlightened, but not the Buddha of our time, is called an Arahant in Pali. Such a person has eradicated all ten hindrances to enlightenment:
- The belief in a permanent personality, ego (Pali: sakkāya-diṭṭhi)
- Doubt, extreme skepticism (vicikicchā)
- Attachment to rites, rituals, and ceremonies (sīlabbata-parāmāso)
- Attachment to sense desires (kāmacchando)
- Ill-will, anger (vyāpādo or byāpādo)
- Craving for existence in the Form world [heavenly realms] (rūparāgo)
- Craving for existence in the Formless world [heavenly realms] (arūparāgo)
- Conceit (māna)
- Restlessness (uddhacca)
- Ignorance (avijjā)
(from Anguttara Nikaya 10.13)
An anagami (non-returner) has completely eradicated the first five hindrances and never returns to earth or any other world system (planet, solar system). Such a person is re-born to a heavenly realm and attains enlightenment from there.
A sakadagami (once-returner) has eradicated the first three hindrances and greatly weakened the fourth and fifth; attachment to sense desires and ill-will. Such a person will be re-born to either the human or heavenly realm and will attain enlightenment there.
A sotapanna (stream-entrant) has eradicated the first three hindrances and will be re-born no more than seven more times and re-birth will either be as a human or a deva in a heavenly realm.