"It is important to use the same calendar."
Translation:Det är viktigt att använda samma kalender.
En kalender can refer to a system for organizing time, like the Gregorian calendar which is what most countries use today. (Russia used the Julian calendar until 1918, which is why the October Revolution happened in November). En almanacka however is a representation of the calendar, like a printed notebook with the days of the year in it, or a wall almanac. Kalender can be used to mean this too, but almanacka can only mean this.
Tack för förklaringen! I was more or less expecting the answer you gave me, because Finnish makes a distinction between kalenteri and almanakka as well. However, the time I have spend in DL has taught me to never take anything for granted, so I had to ask (so I hope you do not feel like you were wasting your time). Just yesterday I learned that in American English (or at least in some varieties of American English) 'pupil' and 'student' are synonymous. I used to be under the illusion that I am fluent in English, but ever since I started studying with the owl, I have noticed that I am nothing of the sort! This is why I have decided to make comments as often as I can, even if it means I get something horribly wrong or ask something that I am fairly certain about. Tack för hjälpen and sorry about the rant.