Ellsberg didn’t scuttle off to Russia. Which is why a lot of folks in the establishment apparatus don’t like/trust Snowden.
Frankly neither Ellsberg nor Snowden are blameless heroes...both were willing participants in the terrible things they wound up exposing. Both dudes were at least partially self-serving. Sadly, their efforts likely haven’t amounted to any serious long-term reform.
Ellsberg has the benefit of history (boomer haigiography, the fact that Nixon sabotaged his own presidency—in part—because the Ellsberg affair drove him mad, etc.). And, yeah, wildly different contexts and public expectations re: national security.
Ellsberg didn't have to scuttle off to Russia. While he certainly faced prison time, he had a realistic expectation of a fair trial, and the first amendment behind him.
If Snowden hadn't got while the getting was good, he'd have spent the rest of his days rotting in Guantanamo Bay while the government just said "Ed Snowden? Never heard of him".