Simply put, strategic communication is a broad category under which public relations falls. To communicate strategically is to develop and manage purposeful communication, working to achieve an organizational goal rather than just distributing information.
a process, or data that satisfies a long term strategic goal of an organization by allowing facilitation of advanced planning, or communicating over long distances usually using international telecommunications or dedicated global network assets to reach the communication targets.
InMillhouse public relations is about selling your company or brand through positively managing the communication channels between a company and its stakeholders. Overall, marketing activities are trying to achieve direct revenue, while PR is trying to drive a positive reputation through an effective PR strategy.