When folk from Shanghai meet, they often give a very slight nod of the head as acknowledgment to each other. When people from Shanghai point at something, they just point at something, as we do. When folk from Beijing meet, they often give a slight rise to their head in acknowledgment of the other, they don't nod. Basically, they 'nod up' in recognition rather than down. When people from Beijing point at something, their finger goes from their chin to the direction, showing that they have thought about it.