Microsoft has decided to rebrand Office Online to simply Office moving forward. They have now chosen to discontinue usage of the “Online” branding with all the Office apps, which means “Word Online” is now “Word,” “Excel on line” is now “Excel,” etc.
Also, it is important to note here that this rebranding only applies to Office apps. There is no change to the branding of the “Online” server products. Specifically Exchange Online, SharePoint Online, Project Online, and Office Online Server.
What is Office Online?
For the uninitiated, Office Online (formerly known as Office Web Apps) is an online suite offered by Microsoft. It allows users to create and edit office documents like Word, Excel, PowerPoint and OneNote. It also includes Outlook.com, People, Calendar and OneDrive, all of which are accessible from a unified app switcher.
Why the change?
In the official blog, they explained the rationale behind this change. Due to the evolved offerings of these apps on multiple platforms, it no longer made sense to use platform-specific sub-brands. Today Office is a solution that spans platforms and devices connected through the cloud, and the web is a critical part of that. This name change reflects Microsoft’s commitment to providing first-rate experiences on each of its supported platforms and devices.
Source - Office Apps Blog