Whilst/while is interesting.

Whilst to me is like being in the midst of something, not just that it is happening somewhere. It seems to have more specificity than 'while'.

"Whilst boarding the train..." Is going to be followed by something personal or hypothetical.

However, I think I'm prone to overlaying a gloss on words that isn't necessarily shared.

As I intimated 'whilst' I would use in philosophical contexts, arguments where there are alternative hypotheticals, say. "Whilst it might be said...".

Most likely it's just subconsciously learned, a product of native/mother tongue learning.

Would be interesting to see the word vectors extracted from literature/media moving over time and across contexts in order to make a comparison.