Usually this means that the wrapper uses the underlying module to do all of the work but provides a different interface. For example DBIx::Simple uses DBI to do all of the actual database interaction but allows you to use its own simplified methods rather than directly using DBI methods. To get a list of columns from a statement handle in DBI, you'd need to do something like:

my @columns = @{$sth->{NAME}};
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whereas in DBIx::Simple, you can just do:

my @columns = $result->columns;
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If you look at the code for columns() method in DBIx::Simple, you will see that it actually does the DBI $sth->{NAME} call, but saves you the trouble of typing the more complex syntax.