I`m pretty sure the top photo is level 12 file quality.  It`d be funny if I was wrong though.  I would say I am 80% sure.

The bottom one has much more color noise.

Oddly, these are much more different than I expected. Based on what was in the other thread, I assumed there was no visible difference between level 10 & 12.

I just thought I would link these two threads,
here is the jpg quality discussion

I'm on my laptop and I see the difference. Top one 12

There is color lost in the bottom one

Even before seeing the other responses I could see very noticeable color noise in the bottom image.  Has to be the top one. 

I agree with KB - I did not expect there to be such a visible difference.

Could be that I should have picked a better subject photo with less noise in the water, and I might have not done the best job of adjusting the shadows. But that's life, no changing in the middle of a discussion. No noise reduction applied, which I never do anyway. Not a particularly sharp zoom lens, 28-135 at 135. f/5.6 ISO 100 at 1/1000 which is acceptable.

This could also be viewed as a monitor test. If someone can't see the difference in color or noise, they may need something that displays more levels and has a better black point.

Here's a really interesting monitor test that someone sent me. In daylight, with the monitor in the shadows, (Sunlight) I can still see the change at 1 on the CRT and my desktop. At night with the indirect lighting bounced off the ceiling, which is what I use when I'm doing my Alamy files, it's easier to see the change from 0 to 1.

http://www.drycreekphoto.com/Learn/Calibration/monitor_black.htm

There are some other issues here. If someone is downsizing to 4MP for Micro, I'm not sure the difference would show as much. The test photo has extreme light and dark areas, blown out highlights to dark shadows. The bird is a dirty white. What do you expect from a seagull?  When I set the black point to the dark of the seagulls eye, the photo turned blue! I also see that I was playing with the in camera contrast and saturation that day, which I now have set to 0 because I didn't like what it was doing to the photos and how it limited the post-processing adjustments.

So many things wrong, which I didn't realize when I was making up the examples last night. Oh well. 

Hi Race,

 Still helpful and also showed your willingness to help. All good things, thanks for your efforts.

Best,
Jonathan

I agree.  It was fun and different for a change.  I wouldn't mind seeing another example.

Could you place one crop on top of the other, so they will change on mouseover?
Here is the example. You need javascript for that, but it will make difference way easier to spot.

View the two images, full size crops of a smaller section of the sample photo. Both saved from the identical TIF original. One as Level 10, one as Level 12. Then the JPGs were converted back (uncompressed) to BMPs so you could view them on the web. The crops are 100% of a small section of that full size uncompressed file.

I've used 10, seems to to satisfy. Speeds up uploads by quite a bit.