WHERE followed by ON clause

What is the semantic difference between the following queries? To me both seemed similar until I executed them on presto. Is this something specific to presto or am I missing something in the SQL standard?

Form 1: All conditions specified in the ON clause.

SELECT
    t1.colA,
    t1.colB,
    t1.colC,
    t2.colD
FROM t1
LEFT OUTER JOIN t2
    ON t1.colA = t2.colA
    AND t1.colB = t2.colB
    AND t1.colE = 1
    AND t2.colF = 2;

Form 2: Some conditions specified in the WHERE clause instead.

SELECT
    t1.colA,
    t1.colB,
    t1.colC,
    t2.colD
FROM t1
LEFT OUTER JOIN t2
    ON t1.colA = t2.colA
    AND t1.colB = t2.colB
WHERE
    t1.colE = 1
    AND t2.colF = 2;

Form 1 results in some rows but form 2 doesn’t but shouldn’t they be equivalent?

Answer

There are two important differences.

First the condition t1.colE = 1. A LEFT JOIN keeps all rows in the first table, regardless of what the ON clause evaluates to. So, t1.colE does not change the number of rows in the result set. However, it does have the strange effect that any columns from t2 when this condition is not true are NULL.

Second the condition t2.colF = 2 has a different effect. This turns the LEFT JOIN into an INNER JOIN, because NULL values do not match the WHERE clause.