SQL Create Trigger Before Delete vs. Foreign Key On Delete

Question

I have one table referencing another. As I see - there are two ways to delete cascading:

What is the difference between CREATE TRIGGER BEFORE DELETE and FOREIGN KEY ON DELETE? Are there any differences in performance?

I came up with this advantage of FOREIGN KEY:
The cascading delete is more obvious because it's attached in the table definition.

Full question:
I have the two tables:
project(id, ...) <- works_on(id, project_id, ...)

What are the differences in

CREATE TABLE works_on (
  ...
  FOREIGN KEY (project_id) REFERENCES project ON DELETE CASCADE
  ...
);

and

CREATE TRIGGER trigger_delete_cascading
  BEFORE DELETE ON project
  DELETE works_on
    WHERE project_id = id;

Answer 1

A FOREIGN KEY will restrict values that can be stored in the project_id column of the works_on table. You will not be able to set a value that does not exist in the project table.

A TRIGGER does not restrict the range of values that can be stored.