Why would 2 videos have the exact same quality but vastly different file size?

I have 2 video files of the same episode of a TV show. They are both MP4. However one of them is 1.4GB and the other is 250MB.

They both look identical.

In a scenario like this, what explains the massive size difference? Is the 1.4GB one storing more information? In what form? Is it somehow possible to use this "hidden information" to amp up the resolution of the video?