Quite the opposite, there are some dialects (e.g. Vologda dialect) where they are pronounced differently, there is a term for that, it's called "о́канье". But the norm is that a native speaker can't differentiate between the two unless he/she has other clues apart from the sound of it.

I can imagine you can detect slight unconscious difference that an educated native speaker introduces by means of computer analysis of sound samples etc., but it's not a phonetically significant difference for a human.