Color science for illustrator and indesign, color not the same with eyedropper tool.

I am trying to copy a color onto a page in indesign and a graph in illustrator. I have all the color info I need, the hex/rgb/cymk values, but the color is different. I understand that may be an issue with the color space but it also occurs when I use the eyedropper tool and copy it from the photo directly. What is the issue that is making these colors different even though they should be the same in theory.