2.12 A picture is a model of reality.

So a fact is a state of things/condition/state of things/status rerum in logical space which is a piece of reality. See 2.063 and 2.11. A picture represents a (purported) fact or existing state of affairs. In Wittgenstein and the Vienna Circle p. 185 he says: “I have inherited this concept of a picture from two sides: first from a drawn picture, second from the model of a mathematician, which already is a general concept. For a mathematician talks of picturing in cases where a painter would no longer use this expression.”