I think all the adverbs bellow mean the same and can be swapped in every context depending on whether the context is formal or informal; in the manner that in formal speech and in written English we can use:
Therefore → (More formal than so or rather a little bit fancier)
But one cannot use the following adverbs in colloquial English and if not, the sentence will sound odd or awkward to native hearer (I mean if someone uses one of the adverbs bellow in colloquial speech); so you can find them mostly in academic papers or in lectures given by e.g. professor and so on:
- As a result
Although the following adverb means the same like the adverbs above, but it is far more formal in comparison with the above-mentioned adverbs:
- (Very formal) → Thus
And the most common and informal equivalent for these all which easily can be found in everyday English is 'so'.
Do you agree with me?