Dialogue is like going out on a date. You never say exactly what you mean but you hint at what you want. You dance around the question instead of coming right out and asking.
Listen to each character speak. If you can’t hear your characters speak, then most probably what you want them to say, most often ought not be said.
What differentiates each character is usually their word choice. This is key in shaping their voices. Forget the sound of the voice, forget the accent, forget pace. Think word choice.