What is the difference between a laughing kookaburra and a normal kookaburra?

A Laughing kookaburra IS a normal kookaburra, and the only one completely native to Australia alone. It is one of four universally recognised species of kookaburra, the others being the Blue-winged kookaburra, Spangled kookaburra and Rufous-bellied kookaburra.