In order to understand why Veda based astrology is unique, we must first understand some fundamental principles that define how celestial bodies and other astronomical subjects of observation are conceptualized in Indian astrology. The planets that are taken into consideration in Vedic astrology are known as Graha. They are intelligent and divine bodies of energy. Graha translates as 'something which grabs or seizes', and this term is a metaphor for the influence or energy exerted upon the minds and affairs of humans by the planets. Although planets do not have full control over human existence in Hindu philosophy, they do play a large role in regulating and distributing merits, restrictions, and well being in the lives and affairs of humans. There are temples throughout India, and abroad dedicated to the Navagraha, or Nine Graha, which are the nine planets recognized in classic Indian astrology. They are among the Deva classification of beings, and are considered living and sacred entities. Graha do play a role in Hindu beliefs and worship in various ways, and astrological observations play a large role in the timings of hoidays and festivals, as both astrology and astronomy are the basis of the Hindu luni-solar calendar called Panchanga. Vedic astrology does not take into account asteroids, comets, Pluto, Neptune, or Uranus as these are either too fleeting or too distant and slow moving to have an impact on the day to day affairs of living humans, in turn making them unreliable in terms of accuracy and relevance. Some don't even have normal paths or orbits. Although many modern, or more recent hybrid systems of astrology attach importance to the outer planets, satellites, and comets, ideas and concepts regarding them are generally considered non-traditional and not specific to the practice or study of astrology in the context of genuine Jyotisha.
Western astrology is a combination of astrological traditions from the Middle East, Mesopotamia, the ancient Helenic Republic (called Greece outside of Europe), newly developed metaphysical ideas and concepts, and more recently concepts and ideas from Vedic/Indian/Hindu astrology and astronomy. Western astrology, as it has been practiced for most of the 20th century, makes use of a certain standard for measurements called the Tropical Zodiac. What this means is all calculations for charts, and other astrological observations are based on the position of the earth in relation to the Sun according to seasons of the year, which are determined by the sun during the equinoxes. For western astrologers, the assumption is that each year, during the Spring and Fall equinoxes (periods of 48 hours when day and night are equal), the Sun is always at the 1st degree of Aries for the Spring equinox, and the 1st degree of Libra on the Fall equinox. This is all relating to the Northen Hemisphere where four season are relevant, which is why calculations in Western astrology are season oriented. This assumption about the positions of the sun being in the same place every year at certain times does not take into account something called Ayanamsa. Ayanamsa is a word that describes a phenomena otherwise known as The Precession of Equinoxes and was observed thousands of yearss ago by sages, seers, and astronomers on the Indian sub-continent, while in contrast was only observed outside of India in the 19th century. The Precession of Equinoxes takes into observation that the Sun while moving along it's apparent or visible path as viewed from Earth does not return to the same position in relation to the fixed stars or constellations which are the locations of the astrological signs. In other words, the Sun is not in the first degree of Aries every year on the 21st of March (Spring equinox). Which in turn means the Sun does not return to the first degree of Libra each year in the Fall. This position changes about 50.29 seconds of one degree each year, and currently, a system of astrology that based it's calculations on these positions of the Sun from around 2,000 years ago are currently out of proportion by an entire sign (30 degrees of a constellation) if not more. On the Spring equinox of 2016,the Sun was at 7 degrees in the sign Meena (Pisces). That is an astronomically correct observation not necessarily related to one branch of astrology or another, although Ayanamsa are, and have always been taken into account in Indian astrology. Hindu astrology does not rely heavily on the Sun or the signs for personality analysis, but if this were so, it would mean the difference between an entire sign between a chart constructed based on Western or 'Greek' astrology, and a Kundali calculated and constructed on the principles and methods of Jyotish. All of this means that there would be an entirely different interpretation of signs, houses, planets, and ascendants in a chart, which is only logical being that Jyotish and Western astrology are two almost completely different astrological systems. Western astrology is actually a combination of different systems collectively termed Western astrology to distinguish it from other branches of living traditional astrological sciences from other parts of Asia, India, and the Middle East.
Based on the above information, five out of six people were not born in the sign they probably assume they were born in, or were told they were born in by some astrologers, newspaper horoscopes, or books in grocery stores. It may be awesome, and there may even be a few things that turned out to be highly accurate in their horoscopes, but it's not based on the stars and planets as they actually are. As I have mentioned before, Western astrology focuses on the Sun as a point of reference for analyzing personal capacities and personality in general. It is a general and false assumption among many astrologers in places where Western astrology or Greek astrology is prevalent, that Indian astrology is based solely on the positions of the Moon, or is based on a lunar calendar. Indian astrology in fact takes into account the position of the Sun, the Moon, and fixed stars or constellations in their true positions for astrological calculations. The applications and concepts unique to Vedic astrology cover all areas of life including perception of ourselves and others, how we perceive reality, how we are perceived by others, desires, skills, capacities, responsibilities, inner and outer resources, creativity, timings of life events, challenges, victories, spiritual growth, and physical aspects of existence. As opposed to referencing astrological signs, solely for examining psychological attributes, and character traits, Indian astrology divides the arc of the entire zodiac into 27 lunar mansions called Nakshatra, each with it's own association to stars, planets, and divinities. Each Nakshatra covers an area of approximately 13 degrees and 20 minutes. Nakshatra are key in defining personal qualities and mindsets during astrological examination, and the planets in an Indian chart cannot be read accurately without referring to the Nakshatra. Nakshatra are also critical in examining personality types, the beginning and end of various planetary periods in a person's life (Dasa), and are key in examining compatibility between two people. Fixed stars, othrwise known as constellations are only utilized for natal chart examination in Western astrology, and there is no firm agreement among most Western astrologers as to the significance of each body or constellation of fixed stars. The Nakshatra play a large role in examining birth charts, and other astrological charts in Vedic astrology, and are of extreme importance for astrologicl divination along with timing events. Pluto, which was discovered in 1930, and remains in one sign for 20 years, does not have a place in traditional Indian astrology. Other planets beyond Saturn are not taken into account, as they have orbits of 84 to 240 years. Planets in Vedic astrology are meant to relate to the dynamic changes that happen over the lifetime of a living human, so these are not included. Within the scope of Vedic astrology, faster moving planets, which are closer to the earth, tend to be more relevant to the lives and affairs of humans, thus yielding a higher degree of accurate information regarding this when examined properly. The ascendant on the earth's horizon, and Moon are examples of these, which is why they are subjects of close examination and importance in Hindu astrology. Indian astrology actually does place emphasis on accurate astronomical observations due to the fact that calculations and interpretation of phenomena rely on these factors. In other words, this science is based on the actual stars overhead as they are in the sky. Among other things that are unique to Hindu astrology is it's use of sidereal calculations to view planetary motions. Although Vedic astrology primarily makes use of a sidereal (viewing planetary motions based on the actual fixed stars) calculation, called Nirayana, it also makes use of the tropical zodiac, called Sayana for certain observations where the movement of the sun in relation to the earth or other planets comes into focus. The longitudinal disparity between Nirayana and Sayana is called Ayanamsa as mentioned above. Within the past 40 years, some Western astrologers who adopted the Nirayana concepts, and various Ayanamsas from Indian astrology began using the term 'Sidereal Astrology' to describe their methods and concepts outside of the context of Indian astrology from which they were taken.