Some parasympathomimetic drugs, like muscarine, stimulate acetylcholine receptors at parasympathetic effector organs. Others, like nicotine, stimulate ganglionic transmission and also stimulate skeletal muscle cells. Compare the types of autonomic responses you would expect from these two drugs.
Nicotine should increase both sympathetic and parasympathetic output since it stimulates ganglionic transmission. Muscarine should result in only parasympathetic responses