There are factors other than aspect ratio to compare when judging strictly by screen shots, which can't be accurately judged when the images are re-sized.
Like?
Like the actual
graphics (shading, detail, color, etc). All you can judge from distorted images with added artifacts is the general shapes of things and which general objects are or aren't included.
Here's a section of the Mega Drive Chiki Chiki Boys shot. The left pic is the raw emulated screen shot, the right is the aspect ratio corrected shot that Tom made. Each one features the exact same section, enlarged four times to the nearest neighbor.
The
full Mega Drive shot uncropped, has 35 colors in the original, and
18900 colors in the 4:3 aspect ratio pic.
Otherwise we might as well only use only shots captured from hardware. I think that any re-sized side-by-sides should be accompanied by the original shots, but they're only necessary when two versions have radically different resolutions and/or some noticeably different proportions of various elements.
Which is virtually every Turbo game that uses the lower resolution. The developers knew these images were going to be stretched to fill the TV screen.
I don't think that any SNES comparison shots will be any higher resolution than 256 wide PCE screen shots. As for the handful of games that are on both PCE and MD, many of the MD games are also 256 pixels wide.
People who say that all developers made games with the same set destination display method in mind give them too much credit. Especially with PCE games, developers picked and chose various ways to depict various aspects of each game. Chiki Chiki Boys is a good example. Much of it was squished to the PCE port's resolution's proportionate size, while other parts were left pixel for pixel the same as the 384 x 224 pixels arcade version. In the end you'll always have parts of a screen that aren't displayed the way it was originally intended. But that's not always a bad thing.
The other thing is that there is no standard display mode for platforms like NES, Genesis and SNES hardware. Each hardware revision displays a different picture (& sometimes sound) and they have different available output methods, ranging from RF-only to RGB. Dithering is the most common aspect argued to be designed strictly for RF display, but most 16-bit era arcade games use it even though they're all intended for RGB display.