Part of this is immediate psychology, and part of it is history. The history aspect is where IRL has an advantage over OL: I can influence which actions are memorable, and use that to craft an impression that is biased with respect to objective reality. With OL play, my ability to use psychological cues to shift the impression of events is limited by the vastly lower bandwidth for communication. And, of course, IRL I don’t have to deal with players who have statistical aids and records of past hands at their finger tips–they only have their memories.

Also, to Dave’s point, stack size can totally be part of table image IRL in a way that it isn’t OL. OL you see a total. IRL you see chips. I control the actual physical size of my stack, and how it is coloured and arranged. So, for example, I can do some subtle things to deemphasize the size of my stack early on, while I’m slowly building and letting the crazy players see too many cards. Once my stack is bigger than most of the table, then I can do things to make it more intimidating–stacking and structuring it so that it’s more in the face of my opponents. Even against solid players with the same real stack value as you, this can give you an advantage because you make them feel like they’re on the defensive.