Jews living in the Diaspora (outside of modern Israel) typically observe two days of chag on holidays that are Yom Tov (holidays where work is forbidden, called yontiff in Yiddish). In Israel, only one day of chag is observed.
Sometimes, depending on the calendar, the Diaspora observes the second day of chag on Shabbat, and the holiday Torah reading pushes the regular weekly Torah reading back a week. Since Israel has only one day of chag, they read the regular weekly Torah reading. Thus, the Parashat ha-Shavuah ends up being different.
When using the “Weekly Torah portion on Saturdays” option on the custom calendar, select the appropriate option depending on where you live (Israeli holiday schedule for those living inside Israel, Diaspora for everyone else).
The Full Kriyah CSV files contain Torah & Haftara readings for Shabbat, Rosh Chodesh, holidays and fast days.
The Weekday CSV files contain Torah readings for Mondays & Thursdays (and Shabbat mincha) when those days don’t co-occur with one of the events above. In other words, these files are intended to be mutually exclusive with the Full Kriyah Shabbat/holiday files.
Triennial CSV files are available for the Diaspora only, as the USCJ/RA has not published aliyah-by-aliyah tables that follow the Israeli sedra scheme.
Note that in September 2013, we replaced the large multi-year fullkriyah.csv file with separate files for each Hebrew year.