Envisioning is not BUFD, but it is a (lean) phase that proceeds inceptions in some cases. The real diference between envisioning and inception is they have different objectives.
- Envisioning is about developing and testing the customer proposition for a new service, usually by developing a prototype that expresses the value proposition and tests execution concepts. Another difference is that envisioning is a key asset driving the business case, the thing that allows the build team to have the freedom that comes with a bucket of money and a heap of trust.
- Inception is about developing a shared understanding of the business objectives with the entire development team, and building a delivery plan for execution. it happens after the business case has been approved.