Strategic communication aims to inform a target audience with relevant, useful and wanted content for the purpose of knowledge.
Marketing communication employs relevant, useful and wanted content to drive desired consumer behavior.
Neither one is better than the other, but they are distinct from each other in their intentions. In the spectrum of journalism to marketing, content strategy is closer to journalism and content marketing is closer to marketing. Content strategy is rooted in the goals and priorities of the entire organization (not just sales), which the created content will help achieve.