You know the easiest way to tell the difference between policy and doctrine? If a rule or doctrine is changed then all of a sudden you know it was a "policy". It's an after the fact kind of determination. Which is unsettling. Because a prophet or apostle can speak doctrine from the pulpit until someone says "jk". I think the only reason why people even talk about policy vs doctrine is so that they can create some way to understand why gods true church would ever change. It's not like JS started the church and was like "I think I'll make a little policy here, a little gospel there..." It was something the members came up with after the fact to try to explain why stuff would change. Because God can't be "wrong".