The voluntary nervous system(somatic) refers to the neurons over which you have control. When you make the decision to move around, these neurons send the impulse from the central nervous system(CNS) to the skeletal muscles.
The involuntary nervous system(autonomic) refers to the neurons that are not under your conscious control. These neurons are responsible for sending impulses from the CNS to the cardiac muscles (heart), smooth muscles (e.g. muscles lining the gut) and glands.
The autonomic nervous system again divides into two antagonistic systems- the sympathetic and parasympathetic nervous system. Also called the “fight or flight” system, the sympathetic nervous system mobilizes the body for activity, accelerating heart rate, constricting blood vessels, and raising blood pressure. On the other hand, the parasympathetic nervous system conserves energy, promoting “housekeeping” functions by slowing heart rate, increasing intestinal and gland activity, and relaxing sphincter muscles.
A chart that should help you organize these terms can be found in the link below.