It's the impact on the belief structure of whoever you're talking to or dealing with. If they go away from the interaction believing something false because you didn't say something, that's lying by omission. Sometimes that info would've been embarrassing to you if revealed. So yeah, the two things can overlap. They can't but don't always. Sometimes withholding private info isn't misleading because it doesn't cause the person to believe anything in particular. They just continue not knowing what they didn't know before. How to think about it morally? I would consider the consequences on the person. If withholding the info will cause them harm in some way, that's a reason to share the info. If there's no harm involved, then privacy can be the major concern.