From my observations, KM25 and KR64 look VERY similar under some situations, but there ARE differences between the two. Perhaps the BIGGEST difference between KM25 and KR64 is the response to subdued, diffuse lighting. As you probably know, this is one situation where KR64 just falls flat on its face. Think of that drab look that a shot taken with KR64 has when taken on a cloudy day. KM25 performs significantly better under these circumstances. And KL200 performs better yet. The other difference is in saturation and contrast. KM25 has slightly higher saturation and slightly lower contrast. These differences are not huge. But they are there. And, as you said, grain is slightly finer and the color range slight smoother.
Originally Posted by PKM-25
The bottom line? In ALOT of situations, there is not going to be much noticeable difference between KM25 and KR64. This is particularly the case with low contrast, sunlit scenes. KR64 does BEAUTIFULLY under such situations. And, in these situations, you would be hard-pressed to see any difference between KR64 and KM25. But under more challenging lighting conditions (especially drab, diffuse light), KM25 generally gives MUCH better results.