The war is officially on: It's Google+ vs. Facebook, in the battle to become the biggest or best global social network.

After rolling out a three-month test phase with limited openings, Google+ is now open to the general public for sign-up and use. Google's new social network site has also integrated its search engine into the design, and expanded its Handouts video chat feature for mobile use and broadcasting.

The company introduced other new Google+ features, including the ability to search for information about topics including cooking or photography, while also giving users the ability to see relevant Google+ users and their posts on those searched-for topics.

Google said on the company's official blog that its Hangouts feature will now be available on camera-equipped smartphones powered by the company's Android software. It said support for Apple iOS devices -- the iPhone -- will be coming soon.

Google+ users can now host an online broadcast, recording it or broadcasting it live.

Hangouts should keep pace with how you socialize in the real world, so today we're launching it on the one device that's always by your side: your mobile phone, Senior Vice President/Engineering Vic Gundotra wrote in a blog post.

Facebook is the world's largest social network, with a reported 750 million global users. But Google+ became the world's fastest growing Internet site during its test phase, before opening to the public. There are differences in the social networks, but how users migrate toward those differences now that Google+ is in a full-compete mode will determine success in the coming months.

Facebook Fighting Back

But while Google+ is now open to the general public and effectively waging war on Facebook to gain social network users, Facebook is also busy updating its site, with the aim of making it more user-friendly.  For instance, Facebook's new news feed will now keep social network users apprised of what what matters most, the company said.

Instead of just sliding up and down according to the most recent updates, Facebook's news feed will now be more like your own personal newspaper, said Mark Tonkelowitz, an engineering manager at Facebook, in a corporate blog post.

Facebook's news feed will focus on the most interesting stories, he said.

In the past, News Feed hasn't worked like that. Updates slide down in chronological order so it's tough to zero in on what matters most, said Tonkelowitz.

Facebook unveiled its new news feed designed to keep users apprised of the most pertinent updates ahead of its f8 developer conference scheduled for Thursday. Facebook, the world's largest social network, also unveiled a new ticker service for real-time commenting from users.

Until now, there hasn't been an easy way to see and chat with your friends about photos, articles, and other things they're posting in real time, Tonkelowitz wrote. The new ticker helps you do just that.

Ticker updates will scroll by in a box on the top right corner of the Facebook homepage. Users wishing to comment can click a box and type without losing their place, Facebook said.

Among the most notable differences between the sites is the real name policy by Google+. The company has sought to force users to provide real names on its network, while some can use Facebook with fake names.

Google chairman Eric Schmidt said last month that Google+, the company's new social network that's come under scrutiny for its real names use policy, is for people to stand for something and who are willing to express themselves. Schmidt said if using a real name creates a danger, for people like those in in Iran or Syria for instance, they don't have to use Google+.

Google+ Seeks Real Name User Identification

Schmidt said, ...in the Western world, what we decided to do was to take the position that we wanted people to be willing to be at least identified by some sort of a real name.

Google's CEO said the reason the company wants Google+ users to use real names, differing from Facebook which allows users to employ fake names, is that Google+ is completely optional.

In fact, many many people want to get in, if you don't want to use it, you don't have to.

Google launched Google+ in June in a limited roll out. By August, Google+ attracted more than 25 million users, making it the fastest growing site ever. Google+ is already popular in the U.S., Brazil and India, but in some other countries it's not diong as well in attracting users and some suspect that's because of the real name policy.

Schmidt addressed the issue during a question and answer session in Augst at the MediaGuardian Edinburgh International TV Festival. The question about Google+'s real name policy was asked by Andy Garvin, a senior strategist at NPR, who was attending the festival but posed his question via Twitter.

How does Google justify its real names only policy on Google+ when it could put some people at grave risk? Garvin asked.

After Schmidt said Google+ was optional if users didn't feel that using a real name was in their best interest Garvin posed another, more pointed question: But you wouldn't use it in Iran or Syria would you? asked Garvin, referring safety issues users in those countries might face using the social network with real names.

Well Iran and Syria are -- let's come back to that because that's a more complicated question. But in the Western world, what we decided to do was to take the position that we wanted people to be willing to be at least identified by some sort of a real name.

Facebook Revenue Reportedly Soaring

But despite the real name difference Google+ hopes will be a differentiator, particularly for advertisers and business professionals, Facebook's growth is so strong that company revenue may double prior estimates, according to one industry observer.

Market researcher eMarketer reports that Facebook's revenue this year may reach $4.3 billion, while previous unconfirmed reports have pegged Facebook's revenue at between $1.5 billion and $2 billion. So while Google+ opens its site to the public, launching a social network attack, Facebook appears to be thriving as the world's largest network.