A Citizen Assembly and a Citizen Jury are more like two points on a spectrum than two separate species, but the differences matter in practice. Assemblies tend to be larger, longer, and more “constitutionally visible,” while juries tend to be smaller, shorter, and optimized for producing a focused judgment on a bounded question within tight time and budget constraints.
- Citizens' assemblies and Juries - local.gov.uk 
The subtle conceptual difference is the metaphor and the output shape. “Assembly” implies a mini-public as a temporary legislature-like body exploring options and tradeoffs, whereas “jury” implies weighing evidence toward a decision, conclusion, or verdict-like recommendation, usually after hearing witnesses in an intentionally structured way.
That rhetorical framing changes how organizers design the process and how the public interprets legitimacy, even when both rely on Civic Lottery selection and facilitated deliberation.
Another practical difference is where they get used. Citizen juries are often chosen for local, technical, or service-delivery questions where a small group can go deep quickly, while assemblies are often chosen for larger national questions (electoral reform, constitutional issues, climate transitions) where broader representation and longer learning time are politically valuable - delib.net