Sukkha-vipassako

Sukkha-vipassako: those who develop just enough tranquility and discernment to act as a basis for advancing to liberating insight and who thus attain nibbāna having mastered only āsavakkhaya-ñāṇa, the knowledge that does away with the fermentation of defilement.

To explain sukkha-vipassako (those who develop insight more than tranquility): Vipassanā (liberating insight) and āsavakkhaya-ñāṇa (the awareness that does away with the fermentation of defilement) differ only in name. In actuality they refer to the same thing, the only difference being that Vipassanā refers to the beginning stage of insight, and āsavakkhaya-ñāṇa to the final stage: clear and true comprehension of the four Noble Truths.