What is different about the spanish calendar?

The main difference between the Spanish and English calendar is that the first one always starts the week with lunes (Monday in English). The second one starts with Sunday (domingo in Spanish). Another difference is that the Spanish calendar always starts the weeks with a lowercase letter and the English calendar the weeks are capitalized.

Lastly, the month comes after the day of the month on the Spanish calendar. For instance, January 18, 2018, on the English calendar is 01/18/2018 but on the Spanish calendar it would say 18/01/2018