A dwarf is an extremely short adult who is less than 58 inches tall. The word midget is considered derogatory and offensive. Both words describe a short person, but refer to different physical characteristics and genetic conditions.
"Midget" refers to a person who is very short, but normally proportioned. The term midget is now rarely used and is considered offensive. But its usage was very common until the end of the twentieth century. It has given way to "short person" or "little person".
"Dwarf" refers to a person with one of several varieties of a specific genetic condition called dwarfism. A dwarf has disproportion of body parts. This is generally caused by a genetic or nutritional disability. Any adult human below the height of 4'10" (147 cm) is considered a dwarf. With reference to legends or folklore, a dwarf is considered a legendary creature resembling a tiny old man, who lives in the depths of the earth and guards buried treasure.
edit Differences in origin of word
Midget, comes from the word midge "small fly" + -et, so that a midget is etymologically a "very small fly". The first reference to the word is found in 1848 in Canada with the meaning "sand fly". In Old English it was "mycg", and it goes back to an Indo-European root, *mu-, which also gave the word mosquito and, by a circuitous route, musket.
The word Dwarf is of Germanic ancestry, coming ultimately from the proto-Germanic root *dhwergwhos meaning "tiny". In Old English it was "dweorg" and meant "person of abnormally small stature".
edit Physical Condition comparison
When the words were coined, "midget" referred to a person who is small in height but doesn't have disproportionate limbs or other body parts. On the other hand, "dwarf" referred to a person who is small and has disproportionate body parts. A midget was small but proportionate while a dwarf's growth was a disability.
However, since the word "midget" is now considered derogatory and offensive, "dwarf" or "little person" describes any adult human less than 147 cms tall.
edit Whom does it affect?
Dwarfism is known to affect humans, animals and plants. Midget is a term used for humans only. In humans, a child for whom one or both parents is affected by dwarfism has a chance of inheriting the condition. Both these conditions affect men and women. It is also caused by hormonal or nutritional deficiency.
edit Differences in associated problems
While there are many problems associated with Dwarfism, midgets are not plagued by these problems. Midgets are just normal people whose height is stunted. In the case of dwarfs, the physical conditions affecting them are: malformed bones, nerve compression, joint disease, and disoriented growth of some organs.
Both midgets and dwarfs have to suffer the psychological or social problems associated with their condition. Social prejudice against their extreme height may reduce their social confidence and opportunites. Sometimes they're mocked and may suffer from low self esteem. Sometimes extreme shortness (height of less than 3 feet) may interfere with their day to day chores.
edit Differences in treatment
Since the conditions are related to genetic problems, there are few treatments available. Dress enhancements such as shoe lifts etc are some of the few ways to change the aesthetics of little people. Growth hormones are rarely used to treat these conditions as the benefits are very small. The most effective means of increasing adult height by several inches is limb-lengthening surgery, though availability is limited and cost is high in terms of dollars, discomfort, and interruption of life.