What is the difference between Vedic and Western astrology?
Both traditions read the same sky. Western astrology anchors the zodiac to the seasons: Aries begins at the spring equinox, whatever stars are behind the Sun that day. Vedic astrology anchors it to the stars themselves. The equinox drifts slowly against the stars, about one degree every 72 years, which is how the two zodiacs came apart.
Neither is a mistake. The Western zodiac is a calendar of light: it tracks the year's mood. The sidereal zodiac is a map of the fixed sky: it tracks position. They answer different questions, and the reason Horoskope keeps both is that a person wants both answers.
The traditions also differ in emphasis. Western practice is rich in character and the aspects between planets. Vedic practice is rich in timing through the dashas, in the Moon's 27 mansions, the nakshatras, and in the divisional charts that zoom into one area of life.
So a chart showing a Leo Sun and a Karka Rashi is not contradicting itself. It is telling you that the light was in Leo and the Moon was among the stars of Cancer, and then reading each for what it is best at. Find your Rashi to see yours.
The page that does this for you: Birth chart calculator.