In the latest 2.8x build (downloaded 25/9)* I found that the view with an orthographic is different between the viewport and render (when the render dimension is in "portrait").
(The plane is 10x10 BU and the Orthographic scale is set to 10)
It looks like in the render the orthographic scale is always applied to the X-axis, but in Blender/rendered viewport the orthographic scale is applied to the longest axis (Y in the case of a vertical/portrait dimensions**)
(Also note that the Orthographic camera is still "backwards")
(*Could've existed before, didn't do any "portrait" renders earlier)
(**like 1080x1920)