In the event wizard when specifying a camera modes you are defining the cropping behavior of the iPad camera. This allows you to have various output ratios such as square and HD video. This setting does not change the camera quality or specify secret functions like connecting to other devices.
Standard: when active will use the full resolution of the camera which is a 3:4 aspect ratio in portrait orientation (4:3 in landscape).
DSLR: when active the camera will be cropped using the same specification as a DSLR camera which is 2:3 ratio in portrait orientation (3:2 in landscape).
Square: when active the camera will be cropped into a square output of 1:1 ratio.
HD video: when active the camera will be cropped into a HD video aspect ratio of 9:16 in portrait orientation (16:9 in landscape).