Office Online is listed prominently as the free option, alongside Office 365 Home Premium (for $9.99 per month) and Office 365 University (for $79.99 for four years). Clicking on the "Learn More" button under Office Online currently takes the user to the Office Web Apps page.
Microsoft has offered Office Web Apps -- the Webified versions of Word, Excel, PowerPoint and OneNote that work in a variety of browsers -- since 2010. Company officials have had problems explaining to normal users how to find and use these apps. Up until now, Microsoft has touted Office Web Apps more as a feature of SkyDrive, its cloud-storage offering soon to be rebranded OneDrive, and/or as an Office 365 feature.
From the chart above, it's clear Microsoft is going to try to make Office Online more discoverable and understandable by the general public. It also seems that Microsoft considers this Office Online rebranding part of Microsoft's next Office wave (codenamed Office 16), give that "O16" is part of the URL path for the new compare site.