Facebook vs Google Plus

Facebook is a social utility that connects people with friends and others who work, study and live around them. Users must register before using the site, after which they may create a personal profile, add other users as friends, exchange messages, and receive automatic notifications when they update their profile. Using Facebook at Work employers can create separate log-ins for employees to use with their Work accounts, or users can link these up with their other profiles to access everything in one place.
Google Plus
Google+ (Google Plus) is a social networking and identity service. It's as a "social layer" that enhances many of Google online properties, and that it is not simply a social networking website, but also an authorship tool that associates web-content directly with its owner/author. Google+ users are interacting socially with Google+'s enhanced properties, like Gmail, +1 button, and YouTube comments.
Face to face in the news:

2015 - Facebook now contains 40M active small business pages - a huge advantage over Google Plus

Facebook has announced some new programs for small businesses, particularly ones that advertise. Facebook also reported that the number of active small business Pages keeps growing — it’s up to 40 million, compared to 30 million last June. And only 2 million of them are active advertisers. The fact that there are so many active businesses that don’t bother with ads seems particularly noteworthy given the declining reach of organic (non-ad) content from Facebook Pages. So Facebook is adding one-on-one chat support for advertisers. Before now, if you were a small business buying ads on Facebook and you needed help, you had to send an email and wait for a response. Czaja said many of those advertisers were asking for live support, so Facebook is giving it to them. It’s rolling out the program in the United States, United Kingdom, and Ireland in the next few months, with more countries to follow.

2012 - Google offers Google+ as an enterprise social network. Facebook should better react

Enterprise social networks a la Facebook have become very popular business tool: companies have learned to use it efficiently and vendors are ready to eat each other for a place in the market (for example, Microsoft ate Yammer). Meanwhile Google, in its business suite Google Apps haven't provided the social networking tool so far. So Google decided to fill this gap with Google+ for Google Apps, which has become available for everybody today. It allows you to use your company page on Google+, not only as a front-end in the social network, but also as an internal collaboration and communication tool. Employees can add messages that are visible only within the company and can't be shared to public. They can also start video conferencing meetings via Hangouts, which will be open only for other employees (and invited external parties).

In addition, Hangouts are integrated now with Google Apps Mail (supports video chat from the inbox), Google Calendar (you can schedule meetings and share meeting links) and Google Docs (you can collaboratively edit documents in Hangouts). Perhaps, Google Hangouts - is the main advantage of Google's social network over other competitors.

Google also promises to add more new features in Google+ for Google Apps soon, and to charge for this service next year.

2010 - GMail and Google Buzz as developer platforms to win over Facebook

In addition to the business version of GAE and cloud storage GS, at the I/O conference Google introduced for developers the new APIs for GMail and Google Buzz. New GMail API allows developers to embed applications directly to emails (as gadgets). These gadgets are currently only available for GMail in Google Apps, and may be added by account administrator from Google Apps Marketplace. For example, Gist and Xobni gadgets display person social information at the bottom of email (as they do it in MS Outlook and Lotus Notes). The Manymoon gadget allows to quickly create a task or project from the email. Taking into account that virtually all enterprise collaborative and social tools use email for notifications, we can expect an avalanche of new GMail gadgets, as well as increasing popularity of this email service in the enterprise segment.

Google Buzz
The micro-blogging service Google Buzz, which will soon also join the Google Apps, has also got the API. First of all it will allow to communicate in Buzz using different third-party clients: web applications (like Socialwok and Meebo), desktop clients (like TweetDeck) and mobile clients (like Seesmic).