Sidrah vs. Parashah — What's the Difference?
Sidrah (plural:
sidrot) is the correct term for the weekly Torah reading — it comes from the word "seder" meaning "order" or "arrangement."
The weekly cycle follows a set
ordering of Torah readings throughout the year.
Parashah refers to the paragraph divisions within the Torah scroll text itself —
either
setumot (סתומות, closed paragraphs; singular:
setumah, סתומה) marked with a small space,
or
petuchot (פתוחות, open paragraphs; singular:
petuchah, פתוחה) that start on a new line.
These are formatting markers in the scroll, not the weekly reading divisions.
Over time, people have come to call the weekly reading a "parashah" as well. This is because each sidrah is named after the opening words of its first parashah.
For example, the first sidrah begins with the parashah that opens "
Bereishit bara Elokim" — so the entire weekly reading is called "Sidrah Bereishit."
Likewise, the second sidrah starts with a parashah that opens with the words "Eleh toldot
Noach" — and so the whole week's reading is called "Sidrah Noach."
Because the sidrah takes its name from a parashah, the two terms became confused — but they refer to different things.