the japan-made fuji's are taiyo yuden's, which are known for their high-quality discs. the taiwanese ones and other brands of discs not made by ty or mitsui are considered inferior.
i odn't know specifics but i imagine this refers to manufacturing quality and expected life of the discs.
however, either data or audio cd's will work just fine for burning audio discs if you're using a computer. some standalone burners prefer audio discs, though i don't know the difference in discs if there even is one.