Biggest one other than avatars being able to sense raava within each other is that Avatars have a habit of touching each other in casual ways the same as they would touch themselves (brushing hair out of faces, holding hands, leaning against shoulders) and have no real sense of personal space because they are the same person, by technicality. This is comes how Aang and Korra both treat their past live's possessions as their own without any thought put to it ("my teapot!"; complete lack of care for historical value when fighting in Kyoshi's outfit).