Lot of stuff may delve into other genres and the clear lines on some genres may not be, but here are some of my thoughts on high fantasy.
Elements:
Ignoring the minutiae - I think we can easily agree on this. Cashing a paycheck is just irrelevant even if it at times money is brought up for a reason to do something (but turns out to not be a real reason). What type of weapons or armor or horse or anything is only important when something is unique to a character (will come back to this). Disease, politics, religion, race, etc. are only important when they are a central problem to something that will affect the world as a whole.
Power is ... - For one thing, I'd say power is a means to an end. Characters aren't trying to be more powerful, wealthier, or whatever. They are trying to achieve some sort of world changing goal and only the powerful or the right person at the right time can make the difference. An ordinary dude can fit right into high fantasy because such things as ideals matter more than measurable ability. However, high fantasy tends to see epic level power. There are quiet, local stories that affect few people that should be high fantasy, but outside of short stories, I'd tend to believe that most high fantasy is also epic. Power is often situationally relevant as opposed to being something that the story worries about, i.e. power serves to further the story and epic stories require epic power. Also, it's common for: the characters to already be godlike in power but just that they don't know it until the climactic moments; characters to be potentially godlike in power and just need the transformation to occur; the characters to regress in awesomeness, which is fairly contrary to how RPGs play.
Stuff - Stuff is a plot device or irrelevant except in one case. Character defining items or, at least, items unique to a character - in other words, items that are really part of a character - show up commonly. You can't take these things away except as a plot device.
Purpose - I think this is the clear difference from epic sword and sorcery. In sword and sorcery, it's just characters doing what they care about - revenge, wealth, whatever. In high fantasy, characters serve a world purpose. They may just be bit players, but the(ir) world depends upon their actions. I think it's possible to play D&D as high fantasy, but how often do the characters really serve a purpose in their world in D&D?
Larger than life - Similar to ignoring minutiae and something I think we can also agree easily on. Dramatic scenes are the ones that matter to the plot. Can have the personal scenes to give the characters character, but they need to have the defend the bridge from all comers moments.
Magic is ... - Wondrous. May not be able to levitate but might be able to bring a snowstorm to a desert. It doesn't tend to follow logic, it just serves a purpose. Fireballs are for dramatic effect not for softening up the bad guys.
Coincidence - Is used all of the time in fiction for different reasons, but it's not something to avoid in HF.
Examples:
John Carter of Mars - It's not even pure fantasy, but this covers the larger than life, the purpose (I would argue), the type of power - greatest swordsman on three worlds and I can only remember one fair fight that he wasn't favored in, yet that's a given and not a goal.
Spellsinger - It doesn't seem like it at first, but the two part opening story is one of saving the world and the way it's done is by summoning one of the powers of the universe. Money is talked about, but it's just an excuse rather than something that has real meaning. Sure, the series is intended to be humorous and there's a genre for that, but Jon-Tom is the preeminent being of the fantasy world and does larger than life stuff (mixed in with the "how do we get out of this misunderstanding" stuff).
Eternal Champion - Only Elric seems to ever slide into sword and sorcery adventures. Even so, most of his stuff I can think of can be lumped in with the rest of the Eternal Champion stories and anytime the story is about the Champion doing his thing, it's high fantasy.
Master of the Five Magics - Don't know how popular this book was, but the story is all about the main character being the special dude who can be the Archimage (I think that's how they spell it in this series), with his mundane problems serving only to achieve the transformation.
A Spell for Chameleon - The first book in the Xanth series. Again, it is also humor fantasy. And, the humor is quite juvenile in the series (more so as it goes on - "The Color of Her Panties"??). But, Bink (that was his idiotic name, right?) is suggested to be omnipotent [add - which makes the story more about his decisions and character and how he affects the world than what he's capable of]. Etc.
Lord of the Rings - Seems obvious why.
Thomas Covenant - Lord of the Ringsish, should also seem obvious, at least once the first book gets over the obnoxious "I'm a leper, so I don't believe in this world" crap at the beginning.
Isn't:
Conan - Sword and sorcery. He might be the preeminent personage of his time and he fights the big kahunas, but he doesn't really serve a purpose.
Wheel of Time - It has elements of high fantasy at times, but even putting aside the obnoxious crap that bogs the series down such that you want to kill something, there's still a bit too much pedestrian fantasy for me to think of it as high fantasy. [add - I realized later that political stories are out of line for high fantasy. Intrigue and politics are part of the backdrop but not the raison d'etre of the stories.]
Deryni - I'd put with WoT in how it has enough mundane stuff, especially politics, to be some sort of midrange fantasy. [add - See above about intrigue and politics.]
I'm sure there's more that I'm leaving out, like how space opera or supers relate or maybe some better examples, but I hope this gives some idea of where I'm coming from. The more I thought about it, the less I thought the Earthdawn game as described would be high fantasy. I'm not saying that we can't do Earthdawn as high fantasy, just that it seemed too much framed within a D&Desque framework to capture all of the elements. Though, it may be the nature of RPGs that high fantasy isn't purely compatible to having a coherent mechanical system.