Barco vs. nave vs. buque vs. navío
In the Spanish language, there are several words to describe a 'ship': 'barco', 'nave', 'buque', 'navío'. Although they all refer to some type of watercraft, their usage can vary depending on the context and the type of ship being referred to.
Barco
This is a general term for any boat or ship, regardless of size or function.
Nos vamos de viaje en un barco.
(We go traveling on a boat.)
El barco tiene muchas ventanas.
(The boat has many windows.)
Nave
'Nave' is normally used when referring to spacecrafts, but it can also refer to ancient ships or boats in literary and formal contexts.
La nave espacial está lista para el lanzamiento.
(The spacecraft is ready for launch.)
Los antiguos egipcios navegaban en grandes naves.
(The ancient Egyptians sailed in large ships.)
Buque
'Buque' refers specifically to large seagoing vessels, such as container ships, cruise ships, and naval ships.
El buque de carga transporta miles de contenedores.
(The cargo ship transports thousands of containers.)
El buque de guerra se prepara para la batalla.
(The warship is preparing for battle.)
Navío
'Navío' is a somewhat old-fashioned term mainly used in literary context. It usually refers to big size boats and used commonly for military vessels.
Este es el navío más grande de la flota real.
(This is the largest ship in the royal fleet.)
Un navío quedó varado en el desierto.
(A ship was stranded in the desert.)
Summary
All of these words barco, nave, buque and navío can refer to a 'ship' but their usage changes according to context. 'Barco' can be used for any boat or ship. 'Nave' often refers to spacecrafts or is used in a historical/literary context. 'Buque' typically describes large sea-going vessels and finally, 'navío', an old-fashioned term often used for military vessels or in a literary context.