The earth’s path is strictly on the ecliptic line. The other planets like Mars, Mercury, Jupiter etc. go round the sun along the ecliptic line but sometimes they are exactly on this line at others slightly north or south of the ecliptic. This passage is called the zodiac.
The Zodiac is a belt of heavens extending on both sides of the ecliptic. It encircles the space through which the planets travel in their orbits.
A belt of the heavens limited by lines about 8o from the eplictic on each side including all apparent positions of the sun and planets as known to the ancients and divided into twelve equal parts called signs of the zodiac. Vedic Astrology say vedic zodiac, which is different from the tropical zodiac used in Western Astrology.
While the tropical (Western) Astrology uses the vernal equinox (the Sun’s position at the beginning of spring) as the starting point for the measurements along the zodiac, the Vedic Astrology uses fixed stars to identify different segments along the zodiac.