The Moon sign is responsible to govern your personality. It is determined by the date and time of your birth and this shows how your inner being actually is. Your personality is the only thing that belongs to yourself in the whole universe and can tell a lot about who you really are. The Sun Sign however rules your individuality and makes you someone in the world. It gives you an identity of your own and has a great influence on your personality too. When the sun and the moon signs are combined together, they give a unique combination of character and traits which are obtained in every human being.
In the Western system of astrology, the same set of Zodiac symbols is used for representing both sun signs and moon signs. With respect to the position of the earth, the position of the sun changes from one zodiac position to another roughly in one month. So, we have 12 sun signs, under which people who were born on a 30-day period are put together. These signs are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. Each sun sign has a particular, pre-defined set of personal traits and character.
A majority of the character traits those are associated with sun signs, deal with ego, creativity, and romantic and sexual preferences. Also, unlike other forms of astrology, these are very easy to understand and one does not need the help of an expert astrologer or an astrological software package to interpret the personality attributes associated with each sun sign.
Moon signs have the same set of zodiac signs. A person may have the sun sign of Libra and the moon sign of Aquarius. Moon sign specifies the position of the moon with respect to the position of the earth at the time of birth of a person. The main difference here is that unlike the sun signs, which correspond to position of the sun on the date of birth, moon signs are determined based on the exact time of birth. As a result, one cannot calculate the moon sign easily. You need to consult a qualified astrologer or an astrology software package for finding out the moon sign.
There is a specific set of pre-defined character sets and behavioral aspects for each moon sign also. It is common that people may find a particular set of moon sign predictions matching their general character and personality more than what is predicted using sun signs. An explanation given for this phenomenon is that the moon has more influence on the person than the sun.
You can have more on moon signs and sun signs available at Cosmichelp.com.