Quick note on the 12vs16.... If you take a 16MP 16x9 sensor and crop it to a 4x3 size, you essentially are just cutting off two 2MP bands on either side of the frame. This isn't a bad thing since image quality tends to degrade as you move away from the center (higher lens aberration). The S7 actually has a higher vertical resolution than the S6, so in terms of finite resolution, the S7's sensor is higher than the S6. The detail difference that many see is typically due to differences in optics. The S7 has a larger field of view, so if you are standing in the same spot taking the same picture, the S6 would appear to have better detail, but in reality the S7's frame has slightly more information (when looking at the same 4x3 image). So to get the exact same image, you would have to take a step or two forward with the S7.... zooming with your feet, like many photographers who use prime lenses.
Now.. these pictures. Looking at the snips you posted, it does look a bit off. That isn't a focus problem, that looks like a processing problem to my eyes. My wife has an S7 and I've found that that thing processing the ever living hell out of images at times. They look great on the phone display but once she takes them off and on to her laptop, you can see it, especially when compared to my 6P. She cares nothing about camera sensors and pixel sizes and all... but on many occasions, she mentions how my shots look a lot better than hers when she crops and resizes to put in, say, a Shutterfly album.
I don't have the originals to verify it, but I think what you are seeing might be the result of Samsung going overboard with the processing software on the S7... I have yet to figure out why they did so... on paper, that sensor should be able to do more with less processing than the previous generation sensor they used.
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