For Mac Users who knows best

I have an Apple Thunderbolt Display, and i plug it to a MacBook Pro (Retina, 15-inch, Mid 2015). What i found out is that i do not get the resolution of my Macbook Pro witch is (2880 x 1800), and the TD is 2560 x 1440), what is the problem ?, any ideas or comments are welcome/ or what to do to fix the issue, Thank you so much.

Duplicate question?:face_with_raised_eyebrow:

Yes Mr J, in case someone here do not reply back.