First off, this is a quick and dirty comparison. It's not meant to be exhaustive (How can it be? It's a comparison of a couple of images!).
This is something for me to satisfy my curiosity about how the two sensors compare and to see what 5 years of progress means to digital photography.
Both images were taken using the Nikon 50mm ƒ/1.8. Both cameras were mounted on a tripod and set to aperture priority at ƒ/6.3. The Nikon D7000 was set to ISO200, the base ISO of the Nikon D70s. Both cameras were set to matrix metering. Both images were taken in RAW and output using Lightroom. All settings in Lightroom were zeroed. The only thing I did in Lightroom was to select a neutral colour for white balance purposes. This was taken at roughly the same spot on both images.
The first thing that surprised me was that for the equivalent aperture and at the same ISO, the D70s (top image) was giving a faster shutter speed.
The second not so surprising thing was that the colour was different. As you can see from both images, the D70s' colour is less vibrant, muted and slightly muggy. The D70s image also looks underexposed a tad. There is also a reddish hue.
The D7000's image is more vibrant. The colours are brighter although the sky is starting to get washed out. Exposure seems almost spot on.
Considering that most Nikon cameras try to preserve highlights, one possible reason for the D70s' higher shutter speed is a lower dynamic range, causing the whites to clip sooner than the D7000.
In terms of colour, alot of information is still held within the RAW files coming from the D70s, they just require more work to extract. Judging from the images produced by the D7000, it is far more difficult to produce a bad image in terms of exposure if you leave the camera to its own devices. Quite a contrast when compared to the D70s.
I experienced the same thing when working on jobs with a friend of mine who owns a D90. I always found that I had less post-processing work to do with the D90. Especially since I believe the colours from both cameras should be at least close to identical before delivering them to customers.
Five years is a long time in digital photography. Quite a difference when compared to film. The D70s' CCD sensor was considered state of the art when it was released with many at the time commenting that CCD technology is the way to go. At the time, CMOS was considered inferior. But as we can see from these two images, CMOS has come a long way. I'm interested to see if CCD will come back into fashion since video is becoming a standard must have in all DSLRs these days.