I want to show you in these two photos the different look when an extension with new floor boards meets old. On the top photo there are a couple of boards that divides the new and old section. This is a good solution when the boards don't have the same width.
On the bottom photo they have tried to aligne the boards without the dividing boards. The old section (darker boards) had carpet on it before and the lighter had been sanded and coated once before. If you have to repair any of the floors try to match the floor boards and use second hand boards if nesseary. These floors are both Tassie oak and look so different in colour becouse one was protected and one was raw (under carpet).