Imposed:

Top down. Directive. Easy to execute and tick off the to-do list.

Limited relevance to operational realities. External consultants can come with generic “learn how to be creative” materials that are not tailored to the reality of participants.
Worst case: management simply demands more innovation without making any cultural changes or providing training.

Unsustainable. People will go to the training, have an enjoyable time, work on generic/illustrative problems. Then they struggle to convert the general skills into their specific circumstances.
As with one-off trainings, the lessons can be quickly forgotten.

Facilitated:

Collaborative. With a mix of facilitative and directive approaches. Working on an actual problem.

In appropriate physical and psychological environments. Usually outside of the office.

More relevant to operational realities as participants are encouraged to, and feel safe enough to share their perspectives and play with ideas.

Sustainable to an extent. An external facilitator is likely to be needed repeatedly over time to bed down the skills. As the group becomes more used to the process, the facilitated sessions will get more effective and productive.

In one-off sessions. the group can at least benefit from having worked on an actual problem.

Enabled:

Self-directed; self-sufficient. Groups are able to be innovative without an external facilitator.

They have created a conducive environment, learned enough practical skills, are conversant with the process of creative problem solving, and feel confident with getting on with it.

This is the most sustainable way to do innovation. It is also the most difficult and costly to implement. The organisation culture will need to be modified, the tools and techniques will have to be practised over time.