LONG and LONG VARCHAR are synonyms for MEDIUMTEXT.

CREATE TABLE t1 (a LONG, b LONG VARCHAR);

DESC t1;
+-------+------------+------+-----+---------+-------+
| Field | Type       | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| a     | mediumtext | YES  |     | NULL    |       |
| b     | mediumtext | YES  |     | NULL    |       |
+-------+------------+------+-----+---------+-------+