Hive uses Java's Timestamp class to manipulate timestamp columns. Unfortunately the textual parsing in Timestamp is done in local time and the internal storage is in UTC.
ORC mostly side steps this issue by storing the difference between the time and a base time also in local and storing that difference in the file. Reading the file between timezones will mostly work correctly "2014-01-01 12:34:56" will read correctly in every timezone.
However, when moving between timezones with different daylight saving it creates trouble. In particular, moving from a computer in PST to UTC will read "2014-06-06 12:34:56" as "2014-06-06 11:34:56".