While going through old question I came to this edit where set-identification tag is changed into part-identification. To me it look previous tag was more fitting but before intervening I wanted to know when to use set-identification vs part-identification.
It's a good question - in general "set identification" is more useful when there's clearly only one set a collection of parts would come from (i.e. a picture of a sealed bag, or half built models) - if you only have one element, unless it's very custom, it's likely to have been in more than one set in which case we can't say which set it's from definitively.
In the case of that question, the parts were in about 5 sets in different quantities, and at least 2 sets had both of them in the quantity shown - in which case changing it to
Part Identification was probably correct, because we typically link to BrickSet or BrickLink, from where you can easily get to the sets that contained a particular element, and compare with other elements in your collection to narrow it down.