I fairly recently came across a note about an observation made by Justin Thomas at the Institute for Botanical Training that a potential definitive differentiator between I. capensis and pallida (common jewelweed and pale jewelweed) may be the number of teeth on larger leaves, with capensis having 9 or fewer, and pallida having many more, up to 14. I checked all of my observations, and a random selection of several dozen of each species on iNat and it seems to hold true. Exciting, if it does prove correct!
In any case, I put together a table that shows many characteristics of the 2 species, marking the ones that are at least suggestive, up through definitive. It only has the 2 species, but (selfishly) those are the only ones around me so they are the most relevant (to me). I have posted the table as a document on OneDrive as the iNat journal feature does not appear to allow tables, and that is really the only effective way to display the information.
I welcome comments, updates, etc., and most importantly - does this match your experience? I have posted a short summary in the journal area , so comments can go there or here.
I look forward to hearing about your experiences!