Snowden released his information to journalists who carefully vetted each item for newsworthiness with the participation of the US government. Then that data was parceled out over many months, so it would remain in daily news cycles and continue to generate commentary over that time, staying in the public's mind.
Manning gave her data to Wikileaks, who posted it online in its entirety.
In fact, in Greenwald's book No Place to Hide, he describes how they held off publishing for several days while waiting for a response from the government. Greenwald was so frustrated with the delays that he considered quitting the Guardian and going on his own. I think that's the idea that eventually turned into The Intercept.
Why did you ignore the SCMP entirely?
As we all know by now, it's illegal to read the leaks unless they're on CNN. "Responsible" journalists from CNN told us as much.
Sort of. They're more responsible in the general sense but also foreign journalists receiving U.S.'s spying capabilities on foreign persons. The aiding and abetting concept is quite appropriate given they published all kinds of NSA attack strategies & subverted companies while the foreign attacks & companies... including in their own countries... didn't get the same treatment. Both attack and defense on the other side got a great boost while U.S. companies simultaneously lost market share.
Quite a bit of damage giving stuff foreigners shouldn't know to foreign journalists. I might be happier if there was a Snowden in all 20+ countries involved in economic and industrial espionage. Instead, it was just what mainly two (U.S. and U.K.) were doing outside the many eyes partnership that extends to Europe. Quite asymmetrical.
The real question is whether there is a greater good to that damage justifying it. I think there was for the domestic leaks but not the foreign ones outside a few. Far as that few, the Belgacom attack is a good example where taking down allies' telecoms over bullshit could have consequences for America past the usual info collection the spies do. Americans should have a conversation about that kind of thing before those acting on our behalf do such acts.
AFAIK, both Manning and Snowden released large quantities of information without reviewing all of it in detail for public interest vs. potential harm, and released it not to the public but to third parties that managed public release. The difference is that Manning released it to Assange and Snowden released it to more responsible journalists.