This table compares the tables and counts for one set of migration data: Level 1 SMS for 2001 with 1991 SMS Set 2 (district level data) and indicates how family status and occupation have been included in 2001 but marital status has been dropped.
Clearly there are a larger number of counts in the data in 2001 compared with 1991.
One of the most important limitations/problems with the 2001 data relates to the disclosure controls that were introduced.