cl-set-difference is an autoloaded compiled Lisp function in `cl-seq.el'.

(cl-set-difference LIST1 LIST2 [KEYWORD VALUE]...)

Combine LIST1 and LIST2 using a set-difference operation.
The resulting list contains all items that appear in LIST1 but not LIST2.
This is a non-destructive function; it makes a copy of the data if necessary
to avoid corrupting the original LIST1 and LIST2.

Keywords supported: :test :test-not :key