Afferent neurons carry information to the brain and spinal cord for analysis. Afferent neurons comprise afferent systems, also known as sensory systems, because they are activated by external stimuli and convey the information to the area of the brain that is responsible for processing a particular stimulus.
Efferent neurons carry information out of the brain. In the peripheral nervous system, they are usually referred to as motor neurons, because most of them carry information from the spinal cord to the various muscles; in addition, they go pretty much to every organ in the body.
An easy way of remembering this is that many words in the English language beginning with the letter ‘E’ designate some type of outward motion, for example; exit, escape.