There is a long tradition of designers creating visions of technological futures. We contrast the properties of two related types of future envisionment, whose commonality is using ‘world building’ to showcase or prototype technological concepts. We consider commercial visions that depict potential future products within possible future worlds, and by extending the concept of Vapourware we term these ‘Vapourworlds’. We contrast Vapourworlds with Design Fictions, a class of envisionment that inherits qualities of criticality and exploration from its familial antecedents’ radical design and critical design. By comparing these two approaches we intend to shed light on both. Superficially these world building endeavours appear similar, yet under the surface an underlying difference in intentionality permeates the substance of both practices. We conclude with a position that by highlighting the contrasts between these practices, mutually beneficial insights become apparent.