Allan, the small & large distinctions are hard to tell the difference sometimes. (Or the Type I, II, III etc. that Janice sometimes uses). When no other difference is apparent, such as slanted vs. straight cent sign, or serif vs. no-serif, etc. have you considered measuring the height?

That is, something like "large 25 = 18mm height"; "small 25 = 13mm height".

These small differences can be difficult to describe efficiently without a photo or side-by-side comparison.