You can prepare and execute a dynamic statement directly with EXECUTE IMMEDIATE. In this case, however, the statement cannot include any placeholders or return any values. All the SQL statements that can be executed with EXECUTE IMMEDIATE are listed in the description of the EXECUTE IMMEDIATE statement, "EXECUTE IMMEDIATE - Execute dynamic statement".
You execute a statement prepared with PREPARE with the EXECUTE statement. If the statement includes placeholders, the corresponding values can be made available via host variables or via a descriptor area that has already been supplied with values in the USING clause of the EXECUTE statement.
In a dynamic SELECT statement, the INTO clause can be used to store the results in host variables or in a previously created descriptor area.