“Tropical relies on the seasons & its based on the seasons. Sidereal especially true sidereal is based on the constellations as it considers ophiuchus & is astronomically accurate. Vedic to a certain extent is also astronomically accurate as it uses nakchatras & padas which base & dissect the the signs off the positions in the sky. So for example if someone’s a Gemini in Vedic astrology however they’re actually an astronomical/true or true sidereal Taurus (13 May - 19 June) Nakchatras & padas would describe Taurus traits. The tropical zodiac is entirely sun-based and the signs are set upon the ecliptic, while the sidereal zodiac is based upon the position of the sun in relation to the star constellations as they appear in the night sky.1 In Vedic or sidereal astrology, the calculation of the Sun passing through the 1st degree of Aries is marked by the Sun passing through the actual observable fixed stars making up the constellation Aries and has nothing to do with the seasons.2 In addition to the twelve signs of the zodiac, the Vedic system also divides the sky into 27 Nakshatras, or lunar mansions, which each have their own characteristics, symbols, and ruling deity”