Answer:
By direction: sensory and motor. Sensory send stimuli to the brain and motor sends stimuli from the brain.
By function: somatic and autonomous. the somatic system is under our conscious control, whereas the autonomous responds automatically to stimuli without conscious thought.
The autonomous system is further categorized into the sympathetic system, which excites the body: "fight or flight," and the parasympathetic, which generally relaxes the body: "rest and digest."