I may be alone on this one, but I think Snowden and Manning are very different.
I think Manning's actions were a lot sloppier than Snowden's. Yes, Manning courageously uncovered crimes, and that's to be acknowledged. But, in my opinion, he wasn't careful enough about the impact of what he was releasing, specifically all the diplomatic communications. He seemed to have a stance that all information should be public by definition. I don't agree with that. I'm too practical -- I don't see how that would work at all. Further, I honestly think it undermined the democratic process to indiscriminately make it all public. Maybe I should be blaming wikileaks for this approach.
In contrast, Snowden has shown the world's people that it's on candid camera on the US tax payer's dime -- illegally and unbeknownst toa almost everyone, including most of Congress. What he's uncovered is fundamentally undemocratic and very, very dangerous. That's worth a blown whistle. In my opinion, it does a disservice to Snowden to lump Manning together with him.