Question

why does the winter and summer solstice occur at different times in the northern hemisphere rather than that of the southern hemisphere​

Answer 1

Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere.