So am I correct in my assessment that it’s more along the lines of a resolution? I ask because I know the Church takes promises and vows rather seriously, and I want nothing to do with either (with the exception of baptismal vows and wedding vows, of course).
A vow binds under pain of sin due to the virtue of religion. As the Code of Canon Law states Can. 1191 §1 A vow is a deliberate and free promise made to God, concerning some good which is possible and better. The virtue of religion requires that it be fulfilled.
I would presume that the confessor in question is using “commitment” in the broad and casual meaning of the word, as it is used in ordinary conversation. When a confessor asks a penitent to commit himself/herself, for example, to the practice of daily prayer or spiritual reading or other pious practice, it is not the same thing as asking a penitent to vow to say the rosary or attend Mass everyday.
One should take private vows and promises to God very seriously indeed.
Lacking the exact formulation of what he said to you, the context, and the specifics…as a confessor myself, I can only say that I would presume – all else being equal – that it is reasonable to assume that “resolution” is synonymous with whatever it is he proposed. A confessor is not in the custom of setting before a penitent a practice that they must adopt as a daily practice for the rest of their life – least of all, under pain of sin.
2102 “A* vow* is a deliberate and free promise made to God concerning a possible and better good which must be fulfilled by reason of the virtue of religion,” A vow is an act of devotion in which the Christian dedicates himself to God or promises him some good work. By fulfilling his vows he renders to God what has been promised and consecrated to Him. The Acts of the Apostles shows us St. Paul concerned to fulfill the vows he had made.