Retained Logic Versus Progress Override:
Different between Retained Logic and Progress Override in P6, The P6 Schedule Options dialog box enables users to select between two options, and Actual Dates to identify how Primavera Software will schedule progressed activities. The article below demonstrates both options.
When using Retained Logic:
the activity that starts out of sequence cannot finish until it’s predecessor has finished. The remaining duration of the out of sequence activity will be scheduled to begin after the predecessor is scheduled to finish. Retained Logic respects the network logic.
When scheduling using Progress Override:
P6 ignores the relationship between the activities and schedules any remaining duration of the “out of sequence” activity from the data date.
See This Video for more information :