The most significant of the changes is a new button that Office 365 users will see a new "File Restore" function in both applications. If you've saved your Office 365 files to OneDrive, you'll be able to restore files in a thirty-day window. In the event that your files are accidentally deleted or corrupted, getting them back is as simple as pressing the button and selecting the files to be restored.
That's a huge win for Office 365 and OneDrive users, but there's more.
The additional changes include:
That last one is also significant, and is a feature that OneDrive's user base has been clamoring on about for quite some time. OneDrive has made it incredibly easy to share files via a link-based system, but unfortunately, never offered users a way to secure those links. That, thankfully, has now changed.
Individually, all these changes are quite good, but taken together, they represent a significant step in the right direction. Kudos to Microsoft for taking the threat of ransomware so seriously, and adding specific features to help protect their users.