How many days does each solar term differ?

There won't be a whole 15 day difference between the two solar terms.

Generally 15. How many days?

The lunar calendar has only 30 or 29 days in a month.

So there will only be one solar term in a month (for example, 15 is a solar term, the last solar term is the 30th of last month, and the next solar term is the 1st of next month), so this month is considered as a leap month.

The agricultural (lunar) calendar is only one kind of calendar, and it is also revised according to people's growing astronomical knowledge. Which is better, the lunar calendar or the lunar calendar?

To put it simply: the Gregorian calendar is easy to remember, and there are 12 months every year, and the size of the month is also stipulated.

The lunar calendar is more suitable for agricultural production in China.

Moreover, solar terms are not a time period (one day), but a time point (that is, the earth's orbit is regarded as a clock, the earth is regarded as an hour hand, and what solar terms are when the earth moves to a specified point).