What does synodic period mean practically?

It tells you how often a planet returns to the same position relative to Earth and the Sun, like how often Mars is at opposition.

Why is it different from the sidereal period?

The sidereal period is measured against fixed stars. The synodic period accounts for the observer also moving in orbit.

Yes, for any two bodies orbiting the same central body.

Calculate the synodic period between two orbiting bodies: the time between successive conjunctions as seen from one body.

Inner Body Period

days

Outer Body Period

days

Synodic Period

779.88 days

Synodic Period (years)2.1352 yr

Synodic Period vs Inner Body Period

The synodic period is the time between identical relative configurations of two orbiting bodies.

1/P_syn = 1/P1 - 1/P2

where P1 and P2 are the sidereal orbital periods.

Find the synodic period of Mars as seen from Earth.

Convert between sidereal and synodic periods.

Compute orbital period from mass and distance.

Relate period to semi-major axis.