Farfel used without any qualification usually means barley. Other kinds
are egg farfel and matzo farfel. Egg farfel is a kind of pasta that,
when cooked, somewhat resembles barley. It would not be kosher for
Pesach (Passover). Matzo farfel would typically be kosher for Pesach.
Farfel kugel is usually a barley kugel.

-bwg