Here's a taste:
For nine seasons, the six beautiful individuals on Friends broke up, fought, made up, got pregnant, and got married, all while rarely leaving their spacious, well-decorated apartments. This was aspirational comedy, about people better off than you. No matter how difficult their trials, the friends never lost their glamorous sheen.
The Office is the anti-Friends. It takes place almost entirely in the office of Dunder Mifflin, a paper sales company in rustbelt Scranton, Pennsylvania. Rather than liking each other, its inhabitants are thrown together. They're average people working jobs most of them despise, forced to deal with one another for eight hours a day. (As the U.K. version of The Office made explicit, most people spend more of their lives with co-workers than their closest friends.)
The Office is galvanized by these telling images, as when Kevin (Brian Baumgartner) told his unimpressed daughter, "This is my filing cabinet" or Ryan the temp (B.J. Novak, who also writes much of the show), confessed directly to the camera, "If I had to, I could clean out my desk in five seconds and nobody would know I'd ever been here. And I'd forget, too." At its core, The Office is about something not very funny at all: the tragedy of adulthood, where possibilities dwindle to limits.
Perhaps no character is more aware of this than Jim. He's the guy who should be boss: he's genuinely funny (unlike Michael), has a good rapport with virtually everyone in the office, naturally leadership qualities, and knows his business. In fact, he knows it too well. He'll never be boss because he can't forget the fact that he makes a living selling paper. Trying to make the best of the future promised by a new account, he could only trail off: "If we were to get this, we wouldn't have to downsize our branch. I could work here for years... years. Years."