A business architecture is an organizing framework of a business, and the documents and diagrams that describe that structure or the people who help build such a structure, respectively.
Architecture documents and standards dictate where policies may need to occur e.g. if you are upgrading to exchange 2010, you might need to upgrade your policy because you might be able to increase the size of the mailbox. In this case, your policy for mailbox sizes may have changed so it would be good to account for that particular change.
Regulatory policies, as used in enterprise architecture for systems design, are used to limit the discretion of individuals, or compel certain types of behaviour. In IT we use policies to control certain types of behaviour such as attachment sizes for mailboxes, or storage space for backups. These policies are usually controlled and monitored using logging mechanisms to enforce system use. As the Service Design architecture is released these policies or 'rules' can be affected.