The Union Component bahaves like the standard SSIS Union All Component, in that it merges together multiple inputs into a single output stream. However, this component is much better at automatically updating when metadata changes, and makes more intelleigent decisions on type coercion. There is no user interface for this component, it assumes that you want to expose every input column as an output, and that input columns of the same name should be coerced into a single output column.

Hint - to see what types are being output from this component, simply double click on the output link.