In lang=en terms the difference between policy and govern
is that
policy is to regulate by laws; to reduce to order while
govern is to require that a certain preposition, grammatical case, etc be used with a word; sometimes used synonymously with collocate.
As verbs the difference between policy and govern
is that
policy is to regulate by laws; to reduce to order while
govern is to make and administer the public policy and affairs of; to exercise sovereign authority in.
As a noun policy
is (obsolete) the art of governance; political science or
policy can be a contract of insurance.