When discussing AutoCAD VPORT (View Ports) covers MicroStation view windows as being the equivalent of the Layout View Port when from my understanding they are closer to the MicroStation Saved Views in functionality and use, particularly with regards to drawing composition. From my perspective AutoCad has no equivalent feature to MicroStation's view windows as the user interface can only display one window through which the user interacts with the drawing/model content.
That is not exactly correct, Acad layout allows you to create different configurations of the view ports; so technically acad provides functionality of view ports. In Microstation the concept of the saved veiws / dynamic view / hyper models is very hard to get and understand from the first time. however, once you master it, it is harder to move away from it, because you control the process.