Microsoft on Tuesday released native versions of its core Office productivity applications for Apple's new ARM-based notebooks.
Collectively tagged as Microsoft 365 for Mac Apps — formerly labeled Office 365 ProPlus — the flagship applications Excel, OneNote, Outlook, PowerPoint and Word have been updated so that they run on the Apple Silicon-powered MacBook Air, MacBook Pro and Mac Mini without requiring translation.
On systems powered by Apple's new M1 system-on-a-chip, macOS 11 — aka Big Sur — uses the Rosetta 2 technology to run existing Intel-based applications. Rosetta 2 translates Intel-based code into code that runs on the M1 SoC.
Rather than translate the code again and again each time the application is launched, Rosetta 2 does the translation once, prior to the first time the app is run, then stores the translated code for subsequent use. On the other hand, native applications do not require such translation and thus launch faster than Intel apps.
To eliminate confusion, developers can packages both the native and Intel versions of an app into a single binary, called a Universal App.
(If all this sounds vaguely familiar to long-time Mac users, it should: The initial iterations of Rosetta and Universal Apps debuted in 2006 with OS X Tiger, to run applications written for the PowerPC processor on then-new Intel-based Macs.)
Users with automatic updates enabled will start to receive the M1-native apps today. Alternately, users can choose App Store from the Apple menu, then select Updates, or from an Office application, pick Check for Updates from its Help menu.

https://www.computerworld.com/article/3601533/microsoft-releases-native-office-apps-for-m1-macs.html