Credo is Latin for, literally, "I believe," and originally meant a particular religious belief.
Now it has the far broader meaning of any system of principles that guide a person or group.
Personality is the combination of thoughts, emotions and behaviors that makes you unique. It's the way you view, understand and relate to the outside world, as well as how you see yourself. Personality forms during childhood, shaped through an interaction of inherited tendencies and environmental factors.