Shares of Facebook (Nasdaq: FB) rose more than 3 percent Monday, trading at midday at $21.81, up 72 cents. But they're still nearly 50 percent below the $38 set at their May 17 initial public offering.

By contrast, shares of social media rival LinkedIn (NYSE: LNKD) rose nearly 3 percent to $111.53, up $3.02, bringing their year-to-date gain to 77 percent.

What's the difference? How come after all the touting of Facebook shares investors have been so badly punished while those who've held onto LinkedIn, its neighbor in Mountain View, Calif., have been so well rewarded?

One reason could be earnings. One doesn't need to be Warren E. Buffett of Berkshire Hathaway (NYSE: BRK/A), the No. 1 investor in International Business Machines Corp. (NYSE: IBM) to understand that.

Facebook, indeed, reported a second-quarter operating loss of $743 million, or 9 cents a share, as revenue rose 32 percent to $1.18 billion.

LinkedIn, by contrast, reported second quarter net income eased 37 percent to $2.8 million, or 3 cents a share, from $4.5 million, or 4 cents a year earlier. Revenue rose 89 percent to $228.2 million.

Indeed, when LinkedIn eliminated certain one-time charges, its non-GAAP net rose 68 percent to $18.1 million.

One reason for the divergence is that Facebook is so heavily oriented to consumers, with a reported 955 monthly active users, compared with LinkedIn, with only 175 million members, virtually all with professional backgrounds including many in the corporate and enterprise market.

At PEHub, editor Jonathan Marino suggested that LinkedIn had effectively destroyed the online business of employee job boards such as Monster Worldwide Inc. (NYSE: MWW), whose market capitalization has sunk to only $756 million from $1.03 billion a year ago.

As Marino pointed out, more than half LinkedIn's revenue in the second quarter derived for its hiring vertical - its internal jobs board that people at work are searching.

Meanwhile, Facebook is trying to win new followers on platforms such as Instagram and trying to add more enterprise companies to its advertiser roster.

Curiously, LinkedIn and Facebook share at least one connection: former LinkedIn CEO and Chairman Reid Hoffman is a director of Zynga (Nasdaq: ZNGA), the online gamer which accounts for about 10 percent of Facebook's revenue.

To be sure, shares of Zynga, of San Francisco, have plunged 70 percent since their Dec. 19 IPO, trading Monday at $28.4, up 12 cents.

Meanwhile, another player in the professional social network sector, Jive Software (Nasdaq: JIVE), of Palo Alto, Calif., also seems to be going places. Its shares have gained 27 percent since their Dec. 15 IPO, trading Monday at $19.05, up 32 cents.

Like LinkedIn, all of its users are professionals, generally behind a wall chosen by their employers, including Charles Schwab Corp. (NYSE: SCHW) and Nike (NYSE: NKE).

Investors will see what Jive's second-quarter performance was when it reports results on Tuesday.

Analysts surveyed by ThomsonReuters expect Jive to report a second-quarter loss of $7 million, or 11 cents a share, on revenue of $26.6 million.

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