We uncovered the following discrepancy between writing ORC files through Pig and Hive:
ORCFile header contains the name of the columns. Storing through Pig (ORCStorage or HCatStorer), the column names are stored fine. But when stored through hive they are stored as _col0, _col1,....,_col99 and hive uses the partition schema to map the column names. Reading the same file through Pig then has problems as user will have to manually map columns.