Close cousins they are, same family. Their heads contain sensory organs, along the edges, that are used to detect the electrical signatures given off by prey items. Such as the electrical output of a small fish's beating heart. These sharks can use these organs to detect these fish while they are buried in the sand. They swim along close to the seafloor and when they detect an electrical signal emminating from the sand, they circle it and home in on it, much like people using a metal detector. Then they dig around and flush the prey item, and as it attempts to escape, they eat it. Very efficient.
The hammerhead's shape is flat across the leading edge and also acts like an aid in turning. It creates a surface that can be used like an airplane's wing. They are extreme manuverable and can turn on a dime. Mostly they are fish eaters and the large ones aggressively take large fish, such as tarpon. There are some YouTube videos showing how these sharks can manuver and attack tarpon that appear to be weak and sick, such as those in the process of being landed by anglers.
The bonnethead is more rounded, like a shovel. Hence their nickname- the shovelhead shark. Their diet consists mostly of crustaceans, but they will eat small fish. They do not grow to reach the same size as a hammerhead. These sharks are very common in the surfzone, where they search using those sensory organs and sight and smell for small crabs, sandfleas, clams, etc. Crabs and shrimp will bury themselves in the sand, leaving only their eyes, located on the ends of stalks specifically for this purpose. The bonnethead can detect them beneath the sand and using it's head as a tool, excavate them from their hiding place and eat them.
A few weeks back I almost landed a huge bonnethead, it was close to five feet in length. A real monster. Hammerheads can grow to be over twelve feet in length.
Some of the club members eat the bonnethead sharks, but specialized care of the flesh is in order, or the meat will taste tainted. Hammerheads are released, and their survivability depends on how they are treated. They will suffer shock and die if not handled properly. Of course both species have teeth and are quite capable of inflicting a vicious bite. Try to be nice to the sharks, but now rattlers......hack them with a bush axe first chance you get.