There are too many non-camera variables on web-sized JPEGs to be able to distinguish between two 35mm cameras. The resampling and sharpening method become much more important than the sensor. Unless you're doing a comparison without knowing which shot is from each camera before making a judgment, what you're seeing is pure bias.
I ran a
test here a while back with
web-resolution MFDB and 35mm photos. I had 50 MFDB and 50 35mm shots in the blind test. LL readers were unable to distinguish between them. So comparing two 35mm cameras together is even more difficult. Whatever you're seeing is placebo.
If you're actually running a blind test you can congratulate yourself, as you are an exceptional pixel peeper.
An alternative explanation is that you are seeing "Canon color" which some claim to be able to spot, and applying any preconceived notions to the shots accordingly. Another alternative is that Nikon users like to jack up the Saturation/Vibrance/Sharpening sliders more than Canon shooters
Finally, there's a good recent thread about "micro-contrast" and another one started by me on "tonality" here as well - recapping those threads: both words are jedi mind tricks, and are not quantifiable. Don't be fooled by them.
