In short, I would say that “training” is objective standards ( the requirements are to run a range IAW regulation and post guidance) while “development” is subjective (actually running the range, interacting with soldiers on it, having the experience of a convoy there, etc .)

I’d also add development requires the individual to mentally engage and want to grow from the experience.  So if a LT gets a class on range operations (training), but then reads more on a related topic, I’d say s/he just crossed the line unit development.

Lastly, I’d say someone can be highly trained, but not very developed and a poor leader.