While Brand strategy indicates the why and the where the brand needs to get to ie. the goal, the creative strategy demonstrates the journey I.e. 'here is how we intend to achieve that goal conceptually'.
Creative strategy is more of an approach that lays out the storytelling needed for the execution of brand strategy. Its about the range of stories the brand tells, the persona and behaviour that the brand illustrates in its journey to arrive at the desired position guided by the marketing strategy.
While some brands can look at revising their creative strategy fairly regularly though keeping the same goal, others may keep moving on the same path ie. telling a longer story, keeping the interest alive with more twists and reveals.
Creative strategy is expressed, over various channels for a specified amount of time, popularly known as campaigns. Not only do campaigns serve as means of expressing the creative strategy and they also provide the desired aspirational spark.
Campaigns could be linked together thematically or work independently but must all contribute to the common business goal. So really, the simple question we need to keep in mind while designing creative strategy is:
“How will the storytelling you are suggesting, help us achieve our key business goal ?”