A correspondent writes to take up a point in an earlier blog, where (in relation to a question about authorship and Shakespeare) I say I always write while and never whilst. He claims he does make a distinction, as follows: 'Fred danced while Ginger walked tells us that they were doing separate things at the same time. Fred danced whilst Ginger walked suggests that Ginger's walking was in distinction to Fred's dancing.' And he feels that 'This meaning of whilst is perhaps a synonym for whereas, except to me it conveys a clearer sense that things are happening at the same time.'
The problem is a local one, in British English. Whilst is virtually unknown in US English. But I can easily believe, because of the ambiguity in while/whilst - words which express both a temporal and a contrastive meaning - that some speakers have introduced a semantic difference, and it sounds as though my correspondent is one. I've heard while/whilst being contrasted in some regional dialects (eg Yorkshire), so he certainly isn't alone. But it isn't a feature of standard English - or, at least, not yet! Dictionaries (such as the OED) treat them as straightforward synonyms. Those who want to make a distinction, then, face a problem, in that they would need to ensure that the context was very clear, to avoid a risk of being misunderstood.
I do share my correspondent's intuition that the contrastive meaning is stronger in whilst than it is in while. But with whereas competently handling that sense, I have no motivation to use it in my idiolect.