Waterfall, Agile & OD
Waterfall asserts that the all project deliverable are be specified upfront, often an unrealistic and inefficient approach.
Agile takes another position, and involves creating high level requirements and an iterative approach to delivery.
OD is akin to Agile in that it ‘chunks’ and groups deliverables, but draws from Waterfall to fix the scope, whilst linking deliverables to Objectives to enable prioritization and audit.
The Skop.es tool-set is the systematization of the Objectives Driven approach.