The main difference is that you begin to feel increasing inner freedom and joy. Let's go back to this question of disease. If, by social conditioning, you go against the laws of nature and health, illness can strike regardless of belief. There is an energy in the body that is independent of your own belief system. It's angry with you when your vibrations conflict with its vibrations, and as a result you feel something amiss.
Life is a process of learning what that law is.
When you hurt another person you are hurting yourself. Anything that offends against the law, regardless of belief, will still offend. The law of karma is a universal law. When we go against it, we suffer. The law of life and the hidden mission in life is to understand why we are born.