Greg patiently explained the difference between Neotropical and Double-crested: on Neotropical, the gular comes to an accute point aiming toward the back of the head, while on the Double-crested it almost forms a right angle. The tail of the Neotropical is also proportionally longer relative to the body, and they eschew open ocean and coastline in favor of protected areas like this marsh.
One Neotropic Cormorant is flying with the DC Corms in this shot. It is one of the right most birds, just under and forward of the uppermost DC Cormorant and slightly above other DC Cormorants. Note the smaller relative overall size, different gular pouch shape and gray (not orange lores). I am posting this since it offers a comparison of these two species in flight. The DC Corms are posted at: http://www.inaturalist.org/observations/180372