What is the fiscal date? And what is the difference with the date?

Question from a beginner in Dexxter 🙂

For expenses, I can enter the date and the fiscal date. What is the difference?
In the learning center, I only saw a use for this when you want to enter an invoice from previous year this year.

Am I good in understanding that I always fill in the date and fiscal date with the invoice date?
Or, for an expense without an invoice, the date of the receipt?

Thanks!