Re: So what's the difference ...
"So what exactly is Microsoft adding to products that have been available for free for many years?"
The ability to add random conversation snippets to the dystopian nightmare of the Graph API. The latest selling points for O365 that they're trying to drive home to businesses are "productivity enhancers." This surfaces all the connections between people in a workplace and, while useful, could easily be abused by micromanagers competing with each other for who has the highest "department engagement score" or whatever.
The main goal isn't selling you Office licenses; it's allowing companies to collect and mine basically every scrap of electronic information trails workers leave behind.