Every planet orbits the Sun on a different plane.
The differences between orbital planes are measured by their angles to Earth’s orbital plane.
The difference is known as orbital tilt or incline.
For instance, Mars’s orbit is tilted at an angle of 1.85° to Earth’s orbital plane.
Orbital plane inclines range from 0.77° (Uranus) to 17.2° (Pluto).
If the planets all existed on the same orbital plane, there would be massive pileups on the heavenly highways.