What is the difference between policy holder and insured on cargo insurance policy?

In some cargo insurance policies identify both policy holder and insured companies, whereas in some cargo insurance policies issued by defining only insured party.

On this article I will try to explain the meanings of "policy holder" and "insured". 

What does policy holder mean on a cargo insurance policy? What does insured mean on a cargo insurance policy.

More importantly are there any differences between these two terms as specified under marine cargo insurance contracts?