For me all the adverbs below mean the same thing, but I need to know more about the nuances between them to be able to use each one in more proper and appropriate situations in my sentences; I would be grateful if you could help me:
- Right away
- At once
The only differences which I can consider between them is that "immediately' implies a faster result than "promptly" though they both always can be swapped. In other hand, "forthwith" is the most formal among the adverbs in my list, then 'immediately' and 'promptly' have the same formality level and finally 'right away' and 'at once' are the most informal choices among these all, though, they can be used in formal and written English too. I need your confirmation or some amendments on my thoughts.