Seems, not only on Windows 10 Mobile but Windows Camera, Photos, Outlook Mail, OneNote & MSN apps have been updated on Windows 10 too as can be seen in the above screenshot.
Changelog is mostly not available but one can expect some UI changes as we have seen in the case of Windows 10 Mobile apps. We however were not able to take screenshots before the update so it is difficult to point out the changes now.
For installing the updates open the Store and go to downloads and check for updates.
