An almanac is not really different from most other calendars, but it also has a great deal of other information in it, like astronomical data needed for farming.

The first almanac in the world was geared more toward farmers than anything else, who needed knowledge about the probable weather during seasons to plant their crops.

Like most calendars, an almanac also specifies which days during the year are holidays, but it also specifies days that are critical to harvest.

My normal calendar does not specify when winter and summer solstice is, but my almanac for this year does.

I do not know if they all do this, but my almanac tells me when a full moon is going to be every month this year.