The attachment image displayed is less than 1/4 of the size of the "[img]" picture. It only calls the full size picture if clicked on, thus with only those wanting to see the original full size clicking on the smaller photo, overall forum bandwidth may be greatly reduced. If many pictures in one post it can speed page load time and reduce server burden.
Cool, found what I wanted to know!
DPS Received Forms- 1/18/11 Online Status - 1/27/11 My Mailbox - 2/12/11 NRA Life Member