The difference between Giant and Midget

When used as nouns, giant means a mythical human of very great size, whereas midget means a little sandfly.

Giant is also adjective with the meaning: very large.

check bellow for the other definitions of Giant and Midget

Giant as a noun:

A mythical human of very great size.
Giant as a noun (mythology):

Specifically, any of the gigantes, the race of giants in the Greek mythology.
Giant as a noun:

A very tall person.
Giant as a noun:

A tall species of a particular animal or plant.
Giant as a noun (astronomy):

A star that is considerably more luminous than a main sequence star of the same temperature (e.g. red giant, blue giant).
Giant as a noun (computing):

An Ethernet packet that exceeds the medium's maximum packet size of 1,518 bytes.
Giant as a noun:

A very large organisation.

Examples:

"The retail giant is set to acquire two more struggling high-street chains."
Giant as a noun:

A person of extraordinary strength or powers, bodily or intellectual.
Giant as a noun:

jotun

Midget as a noun (originally):

A little sandfly.

Examples:

"Although tiny and just two-winged, midgets can bite you till you itch all over your unprotected skin."
Midget as a noun (loosely):

Any small swarming insect similar to the mosquito; a midge
Midget as a noun:

A normally proportioned person with small stature, usually defined as reaching an adult height less than 4'10".
Midget as a noun (sometimes derogatory):

Any short person.
Midget as a noun (attributively):

A small version of something; miniature.

Examples:

"the midget pony"