What are the differences among the words mentioned above? To me "yell at" and "nag at" are informal way to say that someone disapproves something to someone else, with the difference that "yell at" involves the action of actually "yelling" while the other one doesn't necessarily. "Scold" as far as I've understood means the same thing (disapprove something) but it is old fashion. "Reprimand" never heard of it, but Cambridge dictionary suggests that could mean the same thing (in a formal context maybe?).
Like for example, a colleague of mine could be told by my boss that he has done something wrong. If I had to tell the story to a close friend of mine I would say "The boss yelled at X" (because maybe he actually yelled), while to a generic random colleague Y I would say "The boss reprimanded X" (because formally it was what happened, and I don't want to tell him how rude my boss was). "Tell off" apparently is used to express the same thing but in a parenting situation maybe.
Am I wrong? If yes, could you clarify the differences?