By the time this column is published, Google’s shiny, new social network Google+ should have approximately 20 million users. It’s one of the fastest growing services of all time. Have you joined yet? Still waiting for an invite? You can find my Google+ profile here.

I’m asking myself and you this: Is this growth due to the sentiment that Google+ is basically an improved version of Facebook? Or maybe it’s something else?

Google can learn a lot from Facebook, including how it captured more than 700 million users. Let’s hope it doesn’t learn the wrong things. In particular, Google+ doesn’t need brand pages. Let the brands tie in to the core functionality of Google+ with apps and website plug-ins. Businesses are hard-pressed enough to keep their website presence optimized let alone manage another outpost page.

Let’s explore some more Google+ success factors:

1. Open vs. closed networks. Facebook is a closed network. Everything that is shared is held within the sacred “walls” of Facebook. The data it collects – your information – is Facebook’s. This is one main reason many industry pundits have been frustrated by Facebook’s attempts to shut down every effort to export their friends to their own computers. Facebook wants to own the social graph. This is also why brands needed to have fan pages so that they could have a presence in this closed system.

Google wants that data too. Google wants to understand how to bring you more relevant search results and ads. The intersection of search, social, and mobile are a powerful force and Google was handicapped by not having full access to the data. Google makes it very easy for you to liberate your data from Google+. History shows that people get comfortable initially as they explore new experiences in closed systems, but eventually they want the freedom they get from open systems. Just remember the AOL of the 1990s, which brought so many people online in the first place and how eventually they wanted to enjoy the openness of the World Wide Web. Facebook could be the new AOL if it’s not paying attention. Google will now be able to leverage its social data and interest graph to offer new levels of ad targeting across its mighty search and display ad networks and not need to if it chooses to offer any ads so it can make revenue within Google+.

2. Social networking is the fastest growing mobile content category. Google’s Android (its mobile OS) has a huge install base and is growing by 500,000 activations daily. The Google+ Android app is well-polished; it already feels like an integral part of the Android experience for me. All of these activations include access to Google+. What happens to search and social when they are fully integrated in the mobile experience? What happens when I look for a restaurant on Google Maps and see my networks’ +1 reviews on the maps? Or what if I want to go to a movie? Will a search display reviews from my network? Facebook hasn’t even released an iPad app, and has no way to target ads to mobile users currently; Facebook is not ready for mobile.

3. Social networking 3.0. As Google starts to integrate Google+ across its products, the social layer becomes integral to everything we do. Google+’s architecture is based on a better understanding of how people’s networks really work and how information is shared and of interest to different circles. Check out this presentation by former Googler and now current Facebooker Paul Adams.

Will Google eventually even be able to suggest what circles certain friends should fall into so that people don’t have to do all the work manually? Probably.

There are many other things that make Google+ a phenomenal product. The experience from an improved photo viewer (and editor) is one of them. Sparks, is another; it helps you find content based on your interest and even mutes conversations.

There will be many factors that will determine the success of Google+. Nevertheless, let’s end off with a quick visual analysis.

I ran a Feng-Gui visual attention analysis on several screen shots from both Facebook and Google+ and the areas of attention in each are quite different. Yes, they both have streams of updates from your social network (so does Twitter), but the similarities end there.

Facebook stream: All the initial attention focuses on seeing the ad on the right-hand side, followed by which of your friends profile picture changed or who was added by your current friends and which of your friends are available to chat on the left-hand side.

Google+ stream: The first thing you want to focus on is starting a hangout. By the way, the consensus is that it is an “awesome” feature. Google wants you to connect and have a video chat with a group from your network while sharing content from text, to photos, to videos, etc. The next focus would be on adding more people to your network through suggestions.

Rafael Mizrahi, CEO of Feng-Gui commented: “Clearly, the left side of Google+ is cleaner than Facebook, but this is likely to change in the future as more features (and probably ads) are added to Google+ and more real estate will be required in the page to deliver the new features.”

There’s a lot more to be said about all the above. I’d love to know: What do you see as the future and impact of Google+?

P.S. Check out this slideshow on Google+.

Additional images: Heatmaps of FaceBook stream and Google Plus stream