I was doing some research on these, and found this on wikipedia. "The order is awarded to those who have made distinguished achievements in international relations, promotion of Japanese culture, advancements in their field, development in social/occupational welfare or preservation of the environment. Beginning in 2003 the highest ranking medal for the Order of the Rising Sun became a separate order known as Grand Cordon of the Order of the Paulownia Flowers."
as much as wiki can be trusted
I found this on a Japanese medal collection site "The Order of the Rising Sun ("Kyokujitsusho"), established in 1875 as Japanís first national decoration, could be awarded to either military or civilian personnel for meritorious service. There were eight classes to this order, of which only the lowest two were given to enlisted personnel. Foreigners, on occasion, could also be bestowed the award. This medal, the eighth of the eight classes, is in the form of a three-lobed spray of silver Paulownia leaves, with its veins articulated to the obverse, and with a row of four golden kanji characters to the reverse, which translate to "Order of Merit Decoration."
I guess it depends on who translated it? I hope I didn't muddy the water too much, but some of the other sites said it was for merit as well, so maybe it evolved since it was first introduced?