Let's start by defining the difference between a ship and a boat. Roughly speaking, if it sails on fresh water (lakes and rivers), it's a boat; if it sails on salt water (oceans or seas), it's a ship.
In addition to those two broad categories, there are a number of different kinds of passenger vessels:
Barges--Small, self-powered river boats. Generally, they are deluxe and serve gourmet food. I find their cabins are small, but comfortable. They are popular in Europe, and are a