set-difference

set-difference is an alias for `cl-set-difference' in `cl.el'.

(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