They're different units. When chipmakers claim six-sigma (about 0.999999 reliability) they mean that when you order a million chips from them, on average 1 will be bad.
It's not apples-to-apples, but if you look at the number of lines of code executed before a noticeable bug it's in the trillions.
It's not apples-to-apples, but if you look at the number of lines of code executed before a noticeable bug it's in the trillions.