DBIx :: Class :: ResultSetから、次のように読みます。
WARNING
If called on an object, proxies to "new_result" instead, so
my $cd = $schema->resultset('CD')->new({ title => 'Spoon' });
will return a CD object, not a ResultSet, and is equivalent to:
my $cd = $schema->resultset('CD')->new_result({ title => 'Spoon' });
オブジェクトとResultSetの違いを誰かが説明できますか?