OneDrive recently increased its maximum supported file size from 2 GB to 10 GB,[+]. To echo other comments in this thread, it's likely that "Unlimited" storage is a rebranding and publicity move because most paid users were not using anywhere near the 1+ TB they had access to anyways. To me, it seems likely that the file size limit could be lifted for similar purposes soon.

[+] https://blog.onedrive.com/onedrive-now-supports-10-gb-files/