There are two types of repentance, “lower repentance” and “higher repentance.” The first is repentance in the simple sense, regret for sin, and the second the return of the divine soul, intensified attachment to the Creator.

One of the distinctions between the two repentances is that “lower repentance” must be accompanied by confession, in order to uproot and nullify the sin, unlike “higher repentance,” in which the sin is nullified of itself, inevitably. And therefore the repentance of Shabbat Teshuvah and Rosh Hashanah, on which confession is not said, is “higher repentance.”

On Yom Kippur, however, we do say confession, even though the repentance of the day is “higher repentance.” Sometimes it is difficult to uproot sin through the inevitable effect of “higher repentance,” and therefore on Yom Kippur, the last day of the Ten Days of Repentance, we try to uproot the sin by any means possible.

(Likkutei Sichot, vol.4, p. 1360)