Extraverts are mainly concerned with external appearance while introverts are more concerned with the underlying reality.

from wikipedia:

The trait of extraversion–introversion is a central dimension of human personality theories. The terms introversion and extraversion were first popularized by Carl Jung,[1] although both the popular understanding and psychological usage differ from his original intent. Extraversion tends to be manifested in outgoing, talkative, energetic behavior, whereas introversion is manifested in more reserved and solitary behavior

Jung defined introversion as an "attitude-type characterised by orientation in life through subjective psychic contents" (focus on one's inner psychic activity); and extraversion as "an attitude type characterised by concentration of interest on the external object", (the outside world).