The interface for both classes is the same, however the implementation is different. Let me explain a bit how BCP works from user's perspective. The data file contains all the data that will go in. The rows are normally comma separated. Both Microsoft SQL Server and Sybase Adaptive Server provide 2 ways to BCP data.
Second method differs.
Microsoft SQL Server allows to execute inline SQL to get the data going. Well, my friends, I am not about to learn another API set. If anyone knows how to do the same way in Sybase, I am all ears. So if you get errors, check the settings first. Another common source of errors is that the fields in the source data do not match the fields in the target table.