What difference does it really make? Well, in astrology, sidereal signs of the zodiac are connected to the actual constellations. There's much scientific information available and readily accessible for those interested enough to learn the differences, but for the purposes of the zodiac, the biggest difference between the signs of the zodiac that we're familiar with and the sidereal zodiac is that there are thirteen signs of the zodiac instead of the usual twelve.
This difference is due to the number of times the sun passed before the constellations, 13 times. Therefore, while the typical zodiac signs are accounted for, there is one addition; Ophiuchus. This sign celebrates the birth dates between November 30th and December 17th in any given year. While the Sagittarius and the Capricorn share this set of dates in the Western zodiac, Ophiuchus encompasses those dates in the sidereal zodiac. Since then, eight more signs of the zodiac have been added; Crater, Corvus, Cetus, Hydra, Pegasus, Orion, Scutum and Sextans. This is due to the additional passing of the sun in front of the astronomical constellations.
Astrologers lend validity to both sets of scientific theories. While some astrologers seek to discredit others of a different persuasion, there is some common ground. Which one is chosen is strictly a personal preference and, while neither can be utterly or completely disproven, it is important to recognize both as the culmination of centuries of study and cultural belief. The Hindu religion was the first to use sidereal astrological signs in its culture. Using information about the vernal equinox, Hindu astrology accounts for shifts in the equinoxes and therefore, is sidereal astrology. The orbital year, the anomalistic year, Julian year, the Gaussian year and the Tropical year should all be recognized for what they are; "expert" advances in determining time, it's relationship to objects and the movements of the sun, stars and other scientifically substantiated constellations, planets and equinoxes.
As you can see, the constellations are representative of more than starry nights spent on a lakeshore holding hands with the one you love. If you look into the sky, remember all those gone before us w ho made their life's work from looking upward. The amazing world beyond our earth is still not fully understood; but the magic of the stars shows us but a slight image of the many, many wonders of an entire galaxy.