Adjusting for color difference between monitor and TV

I am creating a UI, but there is a large difference between the colors that I can see on my monitor, and my TV.

Is there a way to adjust for the difference between what I see on my monitor and my TV?

As an extreme case, let us assume that my monitor displays 000000 (black), and my TV displays 666666 (gray). I got this value for my TV by checking it via color picker (or some other software, perhaps?)

So to remove the difference, I would simply deduct the difference (666666) from the color value of the TV.

Now, let us say I pick another color, say, aaddff, on my TV, I subtract 666666 from it, it becomes 447799.

Am I in the right direction?

Is there an app or software that can help me with finding out the DISPLAYED color on a monitor/screen?