There are two different aztec calendars. How are they different?

The Aztecs were one of the most advanced pre-Columbian civilizations, although they did not know the use of zero, since they already had an organized system of recording time. This was achieved with two calendars: the xíhuitl or solar calendar and the tonalpohualli or ritual calendar.

Xíhuitl

It was the solar or agricultural calendar, was divided into 365 days, which were divided into 18 months (cempohuallapohualli) of 20 days and a period of 5 days called nemontemi (empty days), which were considered harmful or useless and during which the people fasted and ceased all activity.

Then, according to this calendar, each week had 5 days, being the last day dedicated to the market.

It should be noted that each month of this calendar was related to agriculture, and its use was for civil matters, since it regulated the great ceremonies of the state.

Tonalpohualli

This calendar was composed of 260 days, which were divided into 20 months, 13 days each; where the names of each month was related to an Aztec god and an associated elemental force.

This is because according to the Aztec cosmology, the different gods had to have their own space and dedicated time, to avoid a war in which the world was in the middle and would be affected. That is, they divided the time among their gods to devote to each respect equally.

It should be noted that this calendar was used for ritual purposes and make predictions, which means, it was more divinatory and religious.

Then, one calendar was used for civil activities and the other for ritual activities and was divinatory.