There is no line between the two. It's something that depends on how much effort and time is put into this, what methods were used, etc. But, the world doesn't

There is no line between the two. It's something that depends on how much effort and time is put into this, what methods were used, etc. But, the world doesn't actually care about this specific property, as it has no inherent value. Instead we have various levels of assurance of more practical properties, like safety, but not correctness.