Oliver Queen is was born into wealth and privilege and could never live up to the legacy of his father. Clint was born in rural America, his parents died when he was young and he grew up in foster homes and later in the circus. He is a self-made man, whereas Ollie is always struggling to live up to pre-conceived notions of what he can/should be. He let that define him.
Jeff Lemire, on the inherent differences between Green Arrow and Hawkeye