All of the Asian Pears I grow (Korean Giant is one of them) have lighter colored leaves than any of my European Pears. Pictures on the Internet can be deceiving, but your picture looks very similar to the way that all of my Asian Pears look. Kieffer is thought to be a cross between an Asian Pear and European Pear, but its appearance is much more European, with the darker leaves.
However, in my experience, lighter colored leaves on any apple trees I have ever grown indicates some type of an issue. Sometimes a little fertilizer and lime might do the trick.