The difference is that the constant leaks that serve those in power seldom get to the point where prosecution is considered. Indeed, they are seldom even noticed they happen so often. Shafer writes:
President George W. Bush’s administration declassified or leaked whole barrels of intelligence, raw and otherwise, to convince the public and Congress making war on Iraq was a good idea. Bush himself ordered the release of classified prewar intelligence about Iraq through Vice President Dick Cheney and Chief of Staff I. Lewis “Scooter” Libby to New York Times reporter Judith Miller in July 2003...
And the Obama Administration?
In 2010, NBC News reporter Michael Isikoff detailed similar secrecy machinations by the Obama administration, which leaked to Bob Woodward “a wealth of eye-popping details from a highly classified briefing” to President-elect Barack Obama two days after the November 2008 election. Among the disclosures to appear in Woodward’s book “Obama’s Wars” were, Isikoff wrote, “the code names of previously unknown NSA programs, the existence of a clandestine paramilitary army run by the CIA in Afghanistan, and details of a secret Chinese cyberpenetration of Obama and John McCain campaign computers.”
The secrets shared with Woodward were so delicate Obama transition chief John Podesta was barred from attendance at the briefing, which was conducted inside a windowless, secure room known as a Sensitive Compartmented Information Facility, or “SCIF.” Isikoff asked, quite logically, how the Obama administration could pursue a double standard in which it prosecuted mid-level bureaucrats and military officers for their leaks to the press but allowed administration officials to dispense bigger secrets to Woodward.
And "in 2012, as the presidential campaigns gathered speed, after the New York Times published stories about classified programs, including the 'kill list,' the drone program, details about the Osama bin Laden raid, and Stuxnet, all considered successes by the administration. The reports infuriated Sen. John McCain (R-Ariz.), who essentially accused the Obama White House of leaking these top secrets for political gain."
The final category of leak that Shafer chronicles is perhaps closest of all to what Edward Snowden did, and if you read to the excerpt's end I fully agree with its conclusion:
Sometimes when policy debates get driven underground by secrecy, members of the governing elite band together and tell their story to the press. The most recent example of this banding would be the 2005 storiesin the New York Times about a previous secret NSA surveillance program. The Times series by James Risen and Eric Lichtblau enraged the Bush White House, but there nobody was charged with leaking because the series portrayed itself (accurately, I would guess) as the product of intense, internal government dissent. As Risen and Lichtblau wrote, nearly “a dozen current and former officials” spoke to the paper anonymously about the program “because of their concerns about the operation’s legality and oversight.”
The willingness of the government to punish leakers is inversely proportional to the leakers’ rank and status, which is bad news for someone so lacking in those attributes as Edward Snowden. But as the Snowden prosecution commences, we should question his selective prosecution. Let’s ask, as Isikoff did of the Obama administration officials who leaked to Woodward, why Snowden is singled out for punishment when he’s essentially done what the insider dissenters did when they spoke with Risen and Lichtblau in 2005 about an invasive NSA program. He deserves the same justice and the same punishment they received.
Leaks of classified information in the United States will remain common, regardless of what happens to Snowden, because they frequently serve the interests of people in power—and they won't be prosecuted precisely because they are powerful or connected. That longstanding, bipartisan dynamic is far more important to the norms surrounding official secrets in the U.S. than how a singular, unrepeatable, once-in-a-generation leak is handled. And even if Obama buckled to New York Times pressure and pardoned Snowden tomorrow, would-be leakers couldn't help but be aware that he's also waged an unprecedented war on whistleblowers that preceded the Snowden leaks (even though neither the unjustly persecuted Thomas Drake nor any of the others has done any real harm to U.S. national security.)