As I understand it there are three basic versions of flooring, solid wood, engineered wood as Robbo has described, the top layer being a thin veneer of expensive wood, and printed mdf laminate.
Some people would describe engineered as being inferior to solid but some types of wood don't work very well as a solid piece so engineered allows the use of a wider range of wood types that ordinarily wouldn't be available.
As for printed MDF, from experience it doesn't last very long in a house let alone a boat - even the so called water resistant stuff - particularly near the door where it gets wet more often.