What's correct? If both, what is the difference between these questions?
An example from The Valley of Fear by Sir Arthur Conan Doyle:
MacDonald turned over the letter which Holmes had handed him. «Posted in Camberwell – that doesn't help us much. Name, you say, is assumed. Not much to go on, certainly.
«In notes to Camberwell postoffice.»
«Did you ever trouble to see who called for them?»
The inspector looked surprised and a little shocked. «Why not?»
«Because I always keep faith. I had promised when he first wrote that I would not try to trace him.»
«You think there is someone behind him?»
«I know there is.»
«This professor that I've heard you mention?»
«Well, Mr. Holmes, I admit that what you say is interesting: it's more than interesting – it's just wonderful. But let us have it a little clearer if you can. Is it forgery, coining, burglary – where does the money come from?»
«Have you ever read of Jonathan Wild?»
«Well, the name has a familiar sound. Someone in a novel, was he not? I don't take much stock of detectives in novels – chaps that do things and never let you see how they do them. That's just inspiration: not business.»