I'm not sure why this ticket was closed as invalid. I do believe this is a bug or at least an oversight. For a more succinct example, see: http://jsfiddle.net/g4z3W/
I don't think anyone is suggesting these two functions are interchangeable, but in this particular case they should produce the same result. The offset parent of #box is the document itself, so according to the documentation one might infer that the resulting coordinates should be the same. Since position() includes the margin in the target element's point of origin and offset() does not, they will not produce the same result. This is inconsistent and misleading, and there is no hint anywhere in the documentation that indicates this subtle difference. The point of origin on the target element for position() and offset() should be the same, imo. I think this ticket deserves another peek.