What advantage do I get from attaching something to my house card?
One way makes it an attachment, the other makes it a location.  Which way you would want to play it depends on what your opponent is likely to be able to do.  If they can discard attachments (such as with the card Bought and Paid For), you would want to play it as a location.  If they can get rid of locations, play it as an attachment.

The choice just makes the card flexible.