About the same height and width, I dont know. I would have to see a screenshot of the TCE to be able to maybe find an explanation. The snap is located at the red ring. It snaps the selected uv's to the texture, left,right top,bottom etc. It dosent remap, it just places the uv's on the texture. Hope this helps
Edit: I just understood your same width and height. The texture on the long sides are being stretched because of this. Look at the length of the bricks on the long side compared to the short side in your screenshot.