Each sign of the Zodiac represents so many things. There are differences but also many similarities in the signs because they all belong to the 'whole' picture of astrology and the horoscope.
There are families of signs that are categorized into groups of elements of Fire, Water, Air and Earth. For example, Aries, Leo, and Sagittarius are all Fire Signs, but each one expresses that fiery temperament in a different way. Fire is action oriented and contagious! Imagine three children have a red crayon. The Aries might use it as a sword to poke the air in an imaginary battle. The Leo might melt the crayon on paper to make it look like a Sunburst, and the Sagittarian might use it as a writing implement.
The Water Signs are Cancer, Scorpio and Pisces. They all represent the feeling body. Water as an element has many expressions; it can be a nurturing river like the sign Cancer, go to extremes of heated passion or icy cold like Scorpio, and compassionately embracing or disillusioned by fog like Pisces.
Gemini, Libra and Aquarius are the Air Signs. These represent the mental energies within us. Some people are very quick-witted, curious, and knowledgeable - that's Gemini! Others weigh things out and are considerate of others - that's Libra! And some are true innovators, unique and take those pathways not taken - and that's Aquarius!
For the Earth Signs we have Taurus, Virgo, and Capricorn. Taurus needs to have physical stimulus to his physical senses. Virgo is the organizer and seeks precision and perfection in what he does, while Capricorn is the commander-in-chief ready to handle responsibilities for all.