Which of 24 solar terms is both a solar term and a traditional festival?

In 1 and 24 solar terms, Tomb-Sweeping Day and winter solstice are both solar terms and traditional festivals.

2. Tomb-Sweeping Day, also known as outing festival, outing festival, March festival and ancestor worship festival, is celebrated at the turn of mid-spring and late spring. Tomb-Sweeping Day originated from the ancestral belief and the custom of worshipping spring in ancient times, which has both natural and humanistic connotations. It is both a natural solar term and a traditional festival.

3. Winter solstice, also known as Winter Festival, Asian New Year Festival and Dragon Festival, has both natural and humanistic connotations. It is not only an important solar term among the 24 solar terms, but also a traditional folk festival in China. In ancient times, there was a custom of "eight festivals" to worship the gods and ancestors. Winter solstice is regarded as a big holiday in winter. There is a folk saying that winter solstice is as big as a year, so the ancients called it "sub-year" or "off-year".