Jami Gold, bless her, has great examples as well. And she explains how to pass the baton, i.e., indicate to readers that a POV shift has been made when head-hopping.
Bethany (one of Jami's 2011 commenters) says:
I think it’s like this: the writer is sitting inside the house, throwing windows open, and trying to move the furniture around so the readers can see what’s inside, but the readers only have the view from the windows and nothing more. The task of the writer is to make the windows bigger and arrange the furniture in such a way as that the best view is possible so that the readers feel as though they are inside the house, even though they aren’t. No matter how much we like to think that readers are telepathic and could see inside our minds if we could just put the right words on the page, the reality is that no one is telepathic (at least not that I’ve met), and writers need to allow for that.
Omniscient POV types at the Editor's Blog.
This is really long, and really fantastic. I much recommend it, especially if you wonder what the difference is between these two POVs.
And a short example of how omniscient POV can be made to work using paragraphs as the sections.
Justine Larbalestier says they're just techniques, people! She's right, they are; but if they're done badly, then that is indeed a sign of bad writing, not a bad technique.