The Telluric Threnody
The elves are a magical and powerfully wise race. In their younger years they attempted to elevate the other races by gifting them with Arcane magics, and were the first beings to force their will on the Telluric with magic. This would turn out to be a decision that haunts them to the present day, and is the source of most elven political strife. The cultural differences between high elves and wood elves are mostly based on density of civilization and isolation.
Being of Fey ancestry, elves can sense the rips and holes in the planar fabric and it causes them great sadness and pain. They know on a deeply fundamental level that the world is dying. How most elves approach this fact drives a wedge into their society.
The high elves with their learned Magics, deep philosophy, and cultural awareness have led them to further isolate themselves from the lesser races that they know have lead to the inevitable destruction of the world. Some spend their days in meditation or contemplation, while others pursue pleasure activities as they see fit. The greatest elven minds and families spend their time in research so theoretical and advanced that it is beyond the ken of other races, bent on the purpose of looking for an answer that could be used to help stave off the inevitable.
Some of the wood elves, and a few of their high brethren do not take this approach to the world ending however, and believe that practitioners of magic are the cause of all ills. They desire to help heal the world by preventing these magi from practicing magic, and the easiest and most effective way to do this is by hunting them down. These groups have enough resources and charisma to recruit half elves and gnomes to their cause and enough lack of scruples to hire or trick goblins, orcs, and other darker races to serve their ends.
This dichotomy between elven society has led to a vast misunderstanding of elves in general by outside races, with many common folk among all elves are either peaceful druids or terrorists worth no room in their world view for something in between.