As per definition a rule is a procedure that **must** be followed, however a policy is more of a guidline. As a quick example

 - By viewing forum A you accept that you will not spam, if you do you
   will be banned. *This is a rule **not** a policy*
   
 - As a general policy being a forum based in the US, we will only
   provide official support to English posted questions *this is a
   policy, it's **not** against the rules*

 - And another example is *Honesty is the best policy*, you don't have to be honest.

If they were to be merged I would like to see it as [tag:rules-and-policies]