Hi Tobias / Lal,
These differences in the bala are mentioned in the sekkhabala vagga and the bala vagga.
In the sekkha bala vagga https://suttacentral.net/an5.2/pli/ms hiri and otappa are explained as follows;
(2) “And what is the power of moral shame? Here, a noble disciple has a sense of moral shame; he is ashamed of bodily, verbal, and mental misconduct; he is ashamed of acquiring evil, unwholesome qualities. This is called the power of moral shame.
(3) “And what is the power of moral dread? Here, a noble disciple dreads wrongdoing; he dreads bodily, verbal, and mental misconduct; he dreads acquiring evil, unwholesome qualities. This is called the power of moral dread.
In the Thathagatha Bala Sutta (Named as Ananussutasutta in Sutta Central) https://suttacentral.net/an5.11/pli/ms the buddha says that the 5 bala (Saddha, viriya, hiri, otappa and pragna) helped him attain enlightenment.
In the “Bala Vithaththa Sutta” the 5 powers are mentioned as Saddha, viriya, sati, Samadhi, pragna. Here sati and Samadhi are explained as follows;
(3) “And what is the power of mindfulness? Here, the noble disciple is mindful, possessing supreme mindfulness and alertness, one who remembers and recollects what was done and said long ago. This is called the power of mindfulness.
(4) “And what is the power of concentration? Here, secluded from sensual pleasures, secluded from unwholesome states, a bhikkhu enters and dwells in the first jhāna, which consists of rapture and pleasure born of seclusion, accompanied by thought and examination. With the subsiding of thought and examination, he enters and dwells in the second jhāna, which has internal placidity and unification of mind and consists of rapture and pleasure born of concentration, without thought and examination. With the fading away as well of rapture, he dwells equanimous and, mindful and clearly comprehending, he experiences pleasure with the body; he enters and dwells in the third jhāna of which the noble ones declare: ‘He is equanimous, mindful, one who dwells happily.’ With the abandoning of pleasure and pain, and with the previous passing away of joy and dejection, he enters and dwells in the fourth jhāna, neither painful nor pleasant, which has purification of mindfulness by equanimity. This is called the power of concentration.
From this I think hiri and otappa are for trainees (sekkha) and may be even for anariyas. Sati and Samadhi are for ariyas? An ariya would keep away from immoral deeds more with understanding while an anariya will do it more because or shame and being scared. Hence, the panca bala in the 37 factors for enlightenment include sati and samadi.
Does that make sense?
Thank Tobias for pointing this out. I had read these suttas before but it never occurred to me.