Linear: tend to solve problems by moving sequentially through a series of logical steps. Their strength is their great organization, while their weakness tends to be having trouble getting an analysis going initially.
Nonlinear: tend to view problems configurative, moving back and forth over steps as various pieces of the puzzle become apparent and begin to fall into place. Their strength is their ability to get ideas out and start moving, while their weakness is that their work tends to be unorganized.