Roof rack bars themselves can fit between models, depending on the size and width, but it's likely that you will need different feet and fittings. If both cars are fitted with roof rails that makes things easier as the fittings may work on both, but if it's a flat roof car then it's very likely you will need the specific feet, although the bars themselves may still fit. It's best to check compatibility on the roof rack supplier's website to see what different parts are required for the two cars.