Structured Dialog

Discussion Group
Ideas are discussed in the order they come up in conversation.
Little or no formal structure. Leadership is often informal, but status differences can easily cause anchoring and self-censorship. Senior and/or extroverted members do most of the talking.
Parliamentary Procedure
All speech is addressed to the chair. Clear order of precedence of business. A motion is debated until it is decided or tabled.
Delphi Technique
Primarily for reaching numerical consensus (forecasts, budgets, etc.) 
All communication is in writing, not face to face. 
Each member sends preferred number, with a written justification, to the Delphi coordinator 
Coordinator averages the numbers & summarizes the justifications without revealing who wrote what; distributes result to members 
Each member modifies the numbers and/or arguments based on input received from the coordinator. 
Process continues until time is up or coordinator is satisfied the group is as close to consensus as it will get.
Similar to Delphi but without coordinator; no anonymity. A document circulates among the group for written comments & proposed revisions.
Nominal Group Technique
Silent Writing, Round Robin, Idea Structuring, Discussion, Voting

Comparison Table:  Interacting, Nominal, Delphi Groups