The act of design can be divided into two broad parts: strategy and execution.
Strategic design is the initial exploration, understanding and planning part. Executional design then follows to implement the final solutions.
Strategic design sets the foundation for contextual innovation; by understanding the problem, clarifying directions, imagining possibilities, and evaluating ideas before commencing implementation.
Strategic design goes beyond traditional analysis where situations are broken apart to enable understanding. There is an equally important synthesis component that brings new thoughts and perspectives together as wholes that are greater than their constituents.
This dynamic interplay of blue-sky synthesis and critical analysis is what builds the rich scaffolding for subsequent executional design to grow on.
The focus of strategic design is more high-level; working with the holistic needs of the organisation, project stakeholders and users. In contrast, executional design is necessarily more focused on the functional details of specific use cases.
Strategic designers are the meta-design people you hire before you hire the executional designers.