Translation:The Passover Seder is the first night of the Passover holiday.
Did you know that the holiday of Passover is seven days long in Israel and eight days long everywhere else?
Because the first and last days of the holiday are celebrated similarly to Shabbat (no work, etc.) and while in Israel there is only one such day at the beginning followed by another one at the end, outside of Israel there are two such days at the beginning and two such days at the end. The holiday of Sukkot follows the same pattern
In fact every holiday in the diaspora is "doubled" and is referred to as יום טוב שני של גלויות. It is a fence made by our sages as the new moon was declared in Israel and it took time to spread the word to other regions. Hence they created a one day "buffer zone" (ספיקא דיומא). The only exception to this will be the fast days and Shavuot which is only counted as 50 days from Pesach, without a fixed date.
Actually, even Shavuot is two days long in the Diaspora. However, everything else you said was correct - although the משנה ברורה has a different reason as to why nowadays, with our advanced communication systems, we still have the two days in the Diaspora :)
I never said Shavuot is not two days. My reference to Shavuot was that it does not have a fixed date, hence the גדר is not מחמת ספיקא דיומא, as far as I know.
What's wrong with calling it Pesach instead of Passover? Those of us who keep it call it Pesach in English.
Should be "seder night". Also, Rosh Hashanah is two days even in Israel.
Is there a more literal translation of ליל הסדר? Does it just mean "night of the seder"? I'm guessing ליל is לילה when it's the first word in construct state, is that correct?
So if I'm correct, is the Passover seder referred to in Israel as "night of the Seder," or is this really saying something more like "the night of the Seder is the first night of the Pesach holiday"?
In Hebrew ליל הסדר is the official name of the event but it is mostly called just הסדר. It is somehow like the Israeli currency which is officially called New Israeli Shekel but everybody calls it Shekel or more rarely nowadays Shach (the Hebrew initials of Shekel Chadash).
The Passover Seder was originally called סדר פסח, and it is still used, but also commonly referred to as הסדר ("the Seder"). The night in which the Passover Seder occurs is called ליל הסדר - literally "the night of the Seder", as you wrote. סדר פסח and ליל הסדר are not identical: סדר פסח or הסדר is the ceremony, ליל הסדר is the night in which the ceremony is performed.
I get it wrong: The night of the seder it is the first night of the passover holiday. And like Radagast... has explained not only that my answer is correct, but the 'Passover seder' is wrong.