Yellow peaches have their classic peachy flavor. Inside, the golden flesh of the yellow peach is more acidic, with a tartness that mellows as the peach ripens and softens. White-fleshed peaches are lower in acid and taste sweet whether firm or soft.
http://www.kudamononavi.com/zukan/peach.htm
http://www.kudamononavi.com/zukan/apple.htm#NO8