Color profiles the same yet, when copying and pasting layer to new document the color is completely

Hi all, 

I've spent hours scouring the internet to figure out why my colors aren't matching up. I'm using Adobe photoshop, and I'm copying layers from one document into another. The same program. I'm not switching between programs (as I see that is a lot of other peoples problems with color). 

The color profiles are the same. They are both sRGB. I've tried assigning profiles to both of them ( to Adobe RGB) and attempting pasting my layers in afterwards. The same outcome of different variety of green. I then read to not assign profiles but, to convert. So I did a save as, and tried that. The same outcome. I also tried to set color settings to default, but I never changed them and they are the same as the default (North America General Purpose 2). I attempted to anyways. 

I also read that I needed to embedd color profiles? I'm unsure of what that is, but I read a save as should do it? So I tried that as well. The only thing that seems different from anything I've used before is the fact that these files are on a large paper space. Approximately 60" long. But both are around the same length and yet have different colors. So I'm stumped. 

Any help is greatly appreciated!