We obviously try to steal signs - I would guess just like everyone else. Otherwise not every single football team in the country would have those big signs with pictures of hamburgers or people or different things.
So yeah, just like I said before, the difference is the number of people you have allocated to be able to match up different tendencies and sideline demeanors, as well as the sign themselves, to different plays. That requires a lot of man hours, and man hours require money, an asset which is not equal across-the-board