There are different holiday calendars made for different religions since the holidays differ in each of them. The Jewish holiday calendar follows the Hebrew calendar so it follows different system of dates and holidays. As the months in the Hebrew calendar are different from the Gregorian calendar, the schedule for the holidays are also different.
Here in our site you can get access to the list of all holidays of the Hebrew calendar. So if you belong to the community you can prepare for the holidays in advance and know the exact dates when the holidays fall.