Pioneers are able to explore never before discovered concepts, the uncharted land.
Settlers can turn the half baked thing into something useful for a larger audience. They build trust, understanding and make the possible future actually happen. They turn the prototype into a product.
They build the services that pioneers build upon. They take something that exists and turn it into a commodity or a utility.
How to Start
Start with Town Planners.
Hire Pioneers. Determine an activity that is currently a product but is ready for industrialization to a commodity.
Hire Settlers next. Te job of the settlers is to identify common patterns in the ecosystem.
Hire Town Planners. You should already have them on your team.
Pioneers don't disrupt. There is nothing to disrupt.
Settlers sometimes disrupt (as in product to product substitution in an industry). This is unpredictable.
Town Planners often disrupt past industries. This can be anticipated quite a time in advance.