I have never noticed even the slightest difference between the original raw files and DNG files. But I'm using Windows, and I don't know if that makes that much of a difference. In this instance, I don't believe it should.
Where are the two (CR2 and DNG) JPG images you're showing us coming from? Are these screenshots from the Bridge preview or saves out of ACR or Photoshop viewed in the Mac preview app. In other words, what was the workflow that preceded each image we see in your first post?
When you opened each in ACR did you see different toning settings? What changed in the Toning settings when you reset ACR's preferences? Did you have Auto Toning set in your custom default settings before and now you don't? After you did the reset, did both change to be bright or both change to be darker?
It seems like you're converting to DNG using the DNG Converter. Is this always done before any Adobe software has touched the images or do you do it sometimes after initially reviewing the images in Bridge or ACR?
The only thing I've ever seen, and it was a bug that was corrected some versions ago, was when you had customized your ACR defaults, when opening a native raw file (CR2 in your case) those customized defaults were applied; however, if you converted to DNG using the DNG Converter, then it would reset the customized defaults to the adobe-factory-defaults as it was creating the DNG.
Another possibility is that the CR2 version is from the camera-embedded JPG while the DNG version is computed from the Adobe defaults. This is why I asked if they both became like the bright one or the dark on.
Downloading and checking the properties of each JPG in your first post, it appears to the brighter JPG, the one you call a RAW file, was created with the Mac Photos program, while the DNG one came from Photoshop Elements. If one came from Apple software and one came from Adobe software, why would you expect them to be the same? Maybe one has Apple default processing and one has Adobe default processing and resetting Adobe's settings just erased whatever darken setting you'd accidentally saved as an ACR default, earlier.
To compare CR2 and DNG processing you should copy the CR2 files from the memory card using Finder or Bridge Photo Downloader, then use the DNG Converter to create a DNG then compare the two with Adobe default settings applied to each.
And maybe I'm misinterpreting why the CR2-JPG has Photos as it's creator and both have been run through ACR before making the comparison but without knowing the workflow I assume the simplest situation where two different programs produced the two different JPGs.