Why Airbus would only supply this information on the ground is a little puzzling.
The "Auto" behaviour will be the same for all aircraft types.
On the ground:
A&C responses are inhibited
No responses to Mode S "All calls" (but, as 'Dont Hang Up' says, the aircraft can be selectively called with Mode S)
Another aircraft's TCAS can selectively call your aircraft. It knows your TCAS/Mode S-equipped aircraft is on the ground because of the Mode S data being sent. The other aircraft computes if a Mode C aircraft is on the ground by other methods.