Windows profile vs. "RGB working space"

If I have my newly created .icm in Windows Color Management, doesn't that make it global? Meaning... isn't it already being used once Windows loads the desktop? What's confusing is that Photoshop doesn't affect/preview profiles the same way as RawShooter does when adjusting the profiles in the working space.

For example, in RawShooter, when I have my new profile selected as default in Color Management, and I choose the default sRGB IEC61966-2.1 under RGB working space, the result is a SLIGHTLY reduced brightness compared to when my new profile is selected there in the working space. It's very close, but I can tell it's different... I guess I could say that my new profile results in a slightly brighter result. Either way, is this because I'm doubling up on my working space versus the global windows profile? I'm confused... In RawShooter, I can definitely tell the difference in color/gamma/brightness/etc when I change the working space profile within the application. It seems like it works there.

However, in Photoshop, changing profiles while having the Preview checkbox checked makes NO difference. Yet the default appearance of any images in PS look the same as they do in RawShooter.. but whether it matches the sRGB IEC61966-2.1 or my new one, it's hard to say. I'm not sure why I can't preview profiles in PS. Anyhow...

Doesn't it make sense that one should select the profile that they created with color management software for "working space"? If so, why then does sRGB IEC61966-2.1 look so close to my new profile? I would think that the sRGB option just redirects to whatever Windows is using for the global profile.. that which is set as default in the Color Management settings. Am I correct? Please help me understand what setting has priority over others, what happens when the same profile is selected within the image editing software, and what is going on when sRGB is selected within the software while keeping my calibrated profile in Windows' Color Management.