Compare and contrast northern and southern hemisphere?

A big difference/similarity is seasons.

The northern and Southern Hemisphere have opposite solstices, but their equinoxes are the same. So when the northern half is having summer, the southern half is having winter. But the North's fall is the South's spring, so they both have equal days and nights.

A difference is population/pollution.

Approximately 90% of the population resides within the northern hemisphere. Along with most of the population is most of the pollution too.

Another difference is moon phases.

The northern hemisphere has moon phases change from right to left. Waxing moons gain illumination from right to left, and waning moons lose illumintation from right to left. But in the southern hemisphere, the opposite is true. The moon changes from left to right.

These are the main similarities and differences i can think of. Hope they help!