Faith can be defined as our particular understanding of how the Universe really works.
Faith can be theistic (God(s) is/are involved), or atheistic (no God exists), or agnostic (don't know whether a God is involved).
Belief is about how we live. Our faith, how we think the Universe works, will shape the way we live - it shapes our understanding of right and wrong, and affects the day to day choices we make.
Because belief gives us this framework for making choices, what you believe is crucial to the kind of life you will create for yourself, and how your life choices will affect the rest of humanity.