NUIA can work with both generations of eye trackers.
However, if you were using Tobii 4th generation eye trackers and you want to migrate to the 5th generation, you must first uninstall the Tobii software and drivers for the generation 4th. The same applies if you want to migrate from the 5th generation to the 4th generation.
We recommend to follow our instruction on the article "How can I perform a clean uninstallation of the Tobii software and drivers?"