The definition stage implies prioritizing the user stories and defining the end-to-end program's road map,

The definition stage is used to allow the program teams to understand what the engagement involves, set the terms of the engagement, and determine how best to move forward.

The discovery stage is used to ensure transparency, clarity, and alignment on the engagement and what it's due to deliver to the business.

The design stage ensures a holistic design aligned with business benefits and establishes key responsibilities, roles, timeframes, and deadlines.