I was mainly referring to objectively missing features rather than subjective design differences, though Qt has made a lot of progress over the past few years in terms of feature support. However, a quick scan of the applications on my Mac only turned up one Qt application that I hadn't already recognized as non-native, and that app was the Kindle application (which had an obviously non-native text rendering system, but excusably so).

Qt applications have at least made it to the point where the scroll bars are correct and the menus usually include the standard structure and emacs keybindings work in text boxes, but I've yet to find a Qt application that has a properly integrated help system, and almost every one quits the application when the last window is closed, native toolbars are rare, combo boxes seem to be used frequently where pop-up buttons would be more appropriate, and nobody seems to add any options to the dock icon's context menu. I've seen enough to know that Qt can be a very close approximation if the effort is put forth to make the app act native (probably better than any other cross-platform toolkit), but it's far from free, requires a ton of platform-specific code, and apps that try hard are few and far between.