Western Astrology has its roots in the Roman civilization. The Romans derived it from the Greeks who in turn derived it from the Egyptians.
Vedic Astrology is thus the earliest form of Astrology and is a system that has changed very little over the course of time. Its precision and accuracy as a divination science is unrivalled even today. Many scholars now believe that Astrology traveled to Egypt through the middle east (Babylonian culture). Babylonians had a strong connection with the Vedic civilization flourishing in the northwestern region of the Indian subcontinent and so it can be said that their Astrology was very similar if not completely identical to Jyotish.
The modern day Western Astrology was deeply influenced by the Theosophical Movement.Theosophists as we know were channeling their information from the East - mainly India and Tibet. Somehow over the last century many faults crept into this evolving system such as the use of the astronomically inaccurate Tropical Zodiac.
Tropical Zodiac used in Western Astrology was relevant 2000 years ago but is no longer valid. There is no point in analyzing a chart which does not correspond to the actual heavenly positions of the planets and signs. It is similar to playing music on an out of tune instrument!
Firstly, Vedic Astrology is different than Western Astrology in that Vedic Astrologers use a different Zodiac. There are two Zodiacs, called the Tropical Zodiac and the Sidereal Zodiac. While Western Astrology uses the Spring Equinox as the fixed point of Aries, in the month of March, to start the Tropical Zodiac, Vedic Astrology uses the actual precessed constellation point of Aries, currently in the month of April, to start the Sidereal Zodiac. The difference between the two Zodiacs is currently 23 to 24 degrees. Planets in your Tropical astrological chart below 23 to 24 degrees of a particular sign, say the sign of Aries, will now become recognized by the previous sign, in this case Pisces. In this manner all the planets in your Tropical astrological chart will move backward into the previous degrees of the same or earlier sign.
Secondly, Vedic Astrology uses a Dasha System for making predictions along with placement of planets in different sign in the charts prepared as per the birth time of a native. While Western Astrology doesn't use such kind of system.
Thirdly, the sacred infrastructure of the Vedas can lend a different perspective to a Vedic astrology reading that is not to be found in current western practice. For example, the four pursuits of life, as outlined in the Vedas are: Dharma, Artha, Kama, and Moksha. The Sanskrit word Dharma reflects the purposeful unfolding of self in life. The word Artha, reflects our attitude toward the accumulation of money and the resources necessary to fulfill the self. The word Kama, refers to the rightful fulfillment of the desires of the self. Lastly, the word Moksha, reflects the desire of every soul to enlighten the self from the confinement of this world. These pursuits are qualified and reflected upon in consulting the Vedic astrological chart.