When the focus of the specifying and modelling activity is on a solution, the output...

When the focus of specifying and modeling is on how a solution will meet requirements, the output is referred to as a design. According to the BABOK® Guide v3, design is the usable representation of a solution. It describes the solution components and how they interact to fulfill business needs. This is distinct from requirements, which describe the " what " rather than the " how. "

Requirements = What the solution must do

Design = How the solution will do it

BABOK® Reference:

Requirements Analysis and Design Definition knowledge area explains that specifying and modeling can result in either requirements or designs depending on the focus of the activity.