Last Windows 10 for phones build included the new Office apps. In the above video, Office team gave a quick look at the updated Windows Phone experience for Office. Ben highlighted the richness and fidelity of the apps, including the new palette user interface to make the most of the reduced screen size. He also highlighted a round trip in the mail, calendar and reading experiences on the phone.
Unlike the Office apps on Windows Phone 8 which were never updated since their releases, Office apps on Windows 10 Mobile will be always up to date. The new Word, Excel, PowerPoint and Outlook apps are universal Windows apps. So, whenever Microsoft updates the desktop version of these apps, it will be available on Windows 10 Mobile devices as well.