In a closed urban fantasy, the magical world is secret and no one knows about it. In an open urban fantasy, everyone knows about it. So with a closed fantasy, you have to figure out how the world keeps itself secret, and with an open one, you have to figure out how knowledge of magic has altered the world we know.
Cassandra ClareWe live forever by the grace of human love, which rocked strange children in their cradles and did not despair and did not turn away.
Cassandra ClareLook, it's easy to outsmart a werewolf or a vampire," Jace said. "They're no smarter than anyone else. But faeries live for hundreds of years and they're as cunning as snakes. They can't lie, but they love to engage in creative truth-telling. They'll find out whatever it is you want most in the world and give it to youโwith a sting in the tail of the gift that will make you regret you ever wanted it in the first place." He sighed. "They're not really about helping people. More about harm disguised as help.
Cassandra Clare