If i could only have white bread or white rice, which would be more healthful for me?

Not Much Either Way: Gram for gram white rice has less calories and more protein. But as a serving, one cup of the rice has about three times the calories of one slice of bread. Calculating other relative variables involves differential calculus and a deep knowledge of Madelbrot Sets and is therefore beyond the scope of this discussion. I hope you enjoy your peanut butter and rice sandwich.