Lenny Kleinfeld has written an outstanding piece for READ ME DEADLY in which he brings his scathing humor, trenchant insights and inimitable style to an explanation of what makes screenwriting different from the writing of a novel. You'll find it here:
http://www.readmedeadly.com/2011/09/lenny-kleinfeld-tinker-tailor-n...Read it!
I guarantee you, you'll enjoy it