For starters, there are Circles. Circles are the defining feature of Google+ that allow you to segregate your contacts more intuitively. Everyone isn't your 'Friend'. Some are family, some are co-workers, some are buddies from your golf league, etc. Google refined the social network concept by developing a system that lets you decide on a post by post basis which group or groups of your contacts should see what you are posting.
The drag and drop graphic interface for creating circles and adding contacts is cool--but to me that is a flashy novelty on top of the real value of circles. That is why that enables a drag and drop interface for Facebook that is virtually identical to Google+ Circles misses the mark. I give credit to the developers who basically bought a pizza and a six-pack and developed Circle Hack in one night, but if they really want to impress me they need to make it so I can send status updates, photos, links, etc. to those lists.
Facebook should take a hint, and enable something similar. Right now, I have all kinds of lists in Facebook--Family, High School, Air Force, Infosec, etc.--which help me cut down the noise on the incoming stream by letting me view individual lists, but when I write my own post I can only choose between Everyone, Friends of Friends, Friends Only, and Custom. I can use Custom, but Facebook only lets you set up one Custom profile, so I would have to rebuild the custom profile each time--adding the individual Friends from whatever group I am trying to communicate with.
Next, lets talk about the posts themselves. On Google+, I can say what I need to say...at whatever length I need to say it. I have never been a fan of the 420-character limit for Facebook status updates. I often end up posting the status update, then immediately commenting on my own post to finish my thought--it drives my wife crazy. But, if I wanted a character limit I would post it on Twitter. I don't like having to whittle and edit my thoughts to fit in some arbitrary 420-character box.
Speaking of editing my thoughts--I can do that on Google+. If I discover a typo, or choose to add or rephrase something after I have posted an update or comment, I can just click Edit and make changes at will.