O que há de diferente entre INTERSECT e JOIN?

Ajude-me, por favor.

Crie dados:

CREATE TABLE sub1(id int,name nvarchar(7));
CREATE TABLE sub2(id int,name nvarchar(7));
INSERT INTO sub1 VALUES(1,'one1');
INSERT INTO sub2 VALUES(1,'one1');
INSERT INTO sub1 VALUES(2,'one2');
INSERT INTO sub2 VALUES(2,'one2');
INSERT INTO sub1 VALUES(3,'one3');
INSERT INTO sub2 VALUES(4,'one4');
INSERT INTO sub1 VALUES(5,'one5');
INSERT INTO sub2 VALUES(6,'one6'); 
INSERT INTO sub1 VALUES(NULL,NULL);
INSERT INTO sub2 VALUES(NULL,NULL);

O que há de diferente entre duas consultas:

SELECT * FROM sub1 INTERSECT  SELECT * FROM sub2
SELECT sub1.id,sub1.name FROM sub1 JOIN sub2 ON sub1.id = sub2.id 

O que há de diferente entre INTERSECT e JOIN?

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