I do not think he could make it any clearer that it is actually what he meant!
I believe the issue stems from the classification of Sotapanna in the Sutta. It seems to me that all three (2x Followers and 1x Stream-Enterer) would be referred to as Ariyan but only the last would have realized the Nibbana, plunged into Nibbana.
Viññana Sutta: Consciousness
translated from the Pali by
At Savatthi. "Monks, eye-consciousness is inconstant, changeable, alterable. Ear-consciousness... Nose-consciousness... Tongue-consciousness... Body-consciousness... Intellect-consciousness is inconstant, changeable, alterable.
"One who has conviction & belief that these phenomena are this way is called a faith-follower: one who has entered the orderliness of rightness, entered the plane of people of integrity, transcended the plane of the run-of-the-mill. He is incapable of doing any deed by which he might be reborn in hell, in the animal womb, or in the realm of hungry shades. He is incapable of passing away until he has realized the fruit of stream-entry.
"One who, after pondering with a modicum of discernment, has accepted that these phenomena are this way is called a Dhamma-follower: one who has entered the orderliness of rightness, entered the plane of people of integrity, transcended the plane of the run-of-the-mill. He is incapable of doing any deed by which he might be reborn in hell, in the animal womb, or in the realm of hungry shades. He is incapable of passing away until he has realized the fruit of stream-entry.
"One who knows and sees that these phenomena are this way is called a stream-enterer, steadfast, never again destined for states of woe, headed for self-awakening."
I do not see what other explaination can be given for what would constitute 8 pairs.Raja Sutta: The Emperor
"He/she is endowed with verified confidence in the Sangha: 'The Sangha of the Blessed One's disciples who have practiced well...who have practiced straight-forwardly...who have practiced methodically...who have practiced masterfully — in other words, the four types of noble disciples when taken as pairs, the eight when taken as individual types ...
The four pairs are (1) the person on the path to stream-entry, the person experiencing the fruit of stream-entry; (2) the person on the path to once-returning, the person experiencing the fruit of once-returning; (3) the person on the path to non-returning, the person experiencing the fruit of non-returning; (4) the person on the path to arahantship, the person experiencing the fruit of arahantship. The eight individuals are the eight types forming these four pairs.
So my deduction is that one describes a Stream-Enterer as "One who knows and sees" when talking about 4 individual types and as "One who understands" when talking about 8 Individual types.Sotaapanno Sutta: The Sotaapanna ('Stream-winner')
translated from the Pali by
Maurice O'Connell Walshe
[At Saavatthii the Blessed One said:] "Monks, there are these five groups of clinging. What five? The body-group of clinging, the feeling-group, the perception-group, the mental-formation-group, the consciousness-group of clinging.
"And when, monks, the Ariyan disciple understands as they really are the arising and the passing away, the attractiveness and the danger, and the deliverance from the five groups of clinging, he is called an Ariyan disciple who is a Stream-winner, not liable to states of woe, assured of final enlightenment."
This Sutta defines the Entering of the Stream as: not being destined for states of woe. Which would be in line with my deduction of what constitutes an Ariyan.The Stream
Sota Sutta (SN 48:3)
“Monks, there are these five faculties. Which five? The faculty of conviction, the faculty of persistence, the faculty of mindfulness, the faculty of concentration, the faculty of discernment. When a disciple of the noble ones discerns, as they have come to be, the origination, the passing away, the allure, the drawbacks, and the escape from these five faculties, he is called a disciple of the noble ones who has attained the stream: never again destined for the lower realms, certain, headed for self-awakening.”
Another Sutta which defines The Stream as the Path and a Stream Enterer as one who has the 8FNP is SN 55.5 (can't find an english translation)