(a) Differences between central neural system and peripheral neural system

Central Neural system	Peripheral Neural System
It is a hollow, dorsally placed structure lying along the mid- dorsal axis of the body.	It comprises of the nerves arising from the central nervous system.
It comprises of the brain and the spinal cord.	It is made up of nerves originating from the brain called cranial nerves and those originating from the spinal cord called spinal nerves.
CNS controls all the activities of the body.	The function of PNS is to transmit impulses from the sense organs to CNS and from the CNS to the sense organs.

(b) Differences between resting potential and action potential

Resting potential	Action potential
The potential differences existing between the two sides of neurilemma in a resting nerve fibre is called resting potential.	The potential difference existing between the two sides of neurilemma at a state of depolarisation is called action potential.
Its value ranges from –40 to –90 mV and on an average is –70 mV.	Its value changes from –70 mV through 0 mv to +30 mV.

(c) Differences between choroid and retina.

Choroid	Retina
It is a component layer of the middle vascular coat of the human eye.	It is a component layer of the inner nervous coat of the human eye.
It is rich in blood vessels.	It is rich in neurons.
Its functions is to supply nutrients and oxygen to other parts of eye like retina.	Its function is to form an image of the object over it.