There are 5 classes of Non-Returners, as it is said (e.g. Pug. 42-46):
(1) "He may, immediately after appearing there (in the Pure Abodes) or
without having gone beyond half of the life-time, attain the holy path for the
overcoming of the higher fetters. Such a being is called 'one who reaches
Nibbāna within the first half of the life' (antarā-parinibbāyī).
(2) "Or, whilst living beyond half of the lifetime, or at the moment of
death, he attains the holy path for the overcoming of the higher fetters. Such
a being is called 'one who reaches Nibbāna after crossing half the life-time'
(upahacca-parinibbāyī).
(3) "Or, with exertion he attains the holy path for the overcoming of the
higher fetters. Such a being is called 'one who reaches Nibbāna with exertion'
(sasankhāra-parinibbāyī).
(4) "Or, without exertion he attains the holy path for the overcoming of
the higher fetters. Such a being is called 'one who reaches Nibbāna without
exertion' (asankhāra-parinibbāyī).
(5) "Or, after vanishing from the heaven of the
Aviha-gods (s.
suddhāvāsa), he appears in the
heaven of the unworried (atappa) gods. After vanishing from there he
appears in the heaven of the clearly-visible (sudassa)
gods, from there in the heaven of the clear-visioned (sudassī)
gods, from there in the heaven of the highest (akanittha)
gods. There he attains the holy path for the overcoming of the higher fetters.
Such a being is called 'one who passes up-stream to the highest gods' (uddhamsota-akanittha-gāmī)."