The inner planets are made of rocks while the outer planets are composed of gas.
The inner planets are closer to Sun and are small in size while the outer planets are far away from sun and are larger in size
Parasympathetic nerves govern involuntary actions such as pupil dilation, peristalsis, gland secretions, etc.
The same ligand can bind to different receptors causing different responses (e.g.. acetylcholine). On the other hand, different ligands binding to different receptors can produce the same cellular response (e.g. glucagon, epinephrine).
