Terraform - assume_role_policy - similar but slightly different than standard IAM policy : <p>This page <a href="https://www.terraform.io/docs/providers/aws/r/iam_role.html" rel="noreferrer">https://www.terraform.io/docs/providers/aws/r/iam_role.html</a> mentions:</p>

<blockquote>
  <p>NOTE: This assume_role_policy is very similar but slightly different
  than just a standard IAM policy and cannot use an aws_iam_policy
  resource. It can however, use an aws_iam_policy_document data source,
  see example below for how this could work.</p>
</blockquote>

<p>Is there any reason why the <code>assume_role_policy</code> is different from the <code>standard IAM policy</code>?</p>

<p>Any why?</p>
