Hi
,
You can put your trust in SWI5 - it is a lot 'smarter' than SWWUSERWI. Any discrepancy can probably be explained by the values in other fields of table SWWUSERWI (eg forwarded or substituted or logically deleted).
That's why we don't like looking directly in SAP tables.
NB If you want to know exactly why there's a difference, you'll have to post a detailed example.
cheers
Paul