Vedic (Indian) astrology and Western astrology use different zodiac systems that are currently about 24 degrees apart due to the precession of the equinoxes. This difference increases by about 1 degree every 72 years.
Western astrology uses the "tropical zodiac" fixed to seasons (spring equinox = 0° Aries). Vedic astrology uses the "sidereal zodiac" fixed to actual star positions.
This is why your Vedic Sun sign is often different from your Western Sun sign - both systems are valid but measure different things.