They both taking along time period to form the forest back. Primary approximately thousands of year because they started from an empty land. Secondary approximately only take hundreds of years...
its neither and both... secondary succession merely means that the areas life was destroyed and is growing again... you would have to know the history of the area.
it depends on if the primary succession succeeds and is basically depending on whether anything that happens that could make it be in a state that it would for example burn down that would make it...