Here's how I understand it - a demo might jump in and correct me if I am wrong.
You can use the any of the new reinkers on your old pads.
And you can use your old reinkers on the new pads with the exception of five colors: Basic Black, Basic Gray, Marina Mist, Perfect Plum and Tempting Turquoise. Those colors were reformulated for the new pads and so the old reinkers are not recommended for use on them.
The real voyage of discovery consists not in seeking new lands but in seeing with new eyes...