Ferrovia vs. caminho-de-ferro vs. linha férrea vs. via férrea
While all these terms refer to rail transport, the choice depends largely on regional usage (Brazil vs. Portugal) and technical nuance (the general system vs. the specific physical tracks). Ferrovia and caminho-de-ferro generally refer to the system, whereas linha férrea and via férrea refer to the infrastructure.
Ferrovia
B1This is the most common term used in Brazil to describe a railway system or a specific railroad company. It refers to the mode of transport or the infrastructure as a whole business or sector.
O governo anunciou novos investimentos na ferrovia norte-sul.
(The government announced new investments in the north-south railway.)
O transporte de carga por ferrovia é mais barato.
(Cargo transport by railway is cheaper.)
Essa ferrovia foi construída no século vinte.
(This railroad was built in the twentieth century.)
Caminho-de-ferro
B1This term is used almost exclusively in European Portuguese (Portugal) and Africa (Angola, Mozambique). It is the classic definition of the railway system. In Brazil, it sounds archaic.
Os trabalhadores do caminho-de-ferro estão em greve.
(The railway workers are on strike.)
Portugal tem uma vasta rede de caminho-de-ferro.
(Portugal has a vast railway network.)
Vamos visitar o museu do caminho-de-ferro amanhã.
(We are going to visit the railway museum tomorrow.)
Linha férrea
B2This refers to a specific route or railway line connecting two points. It focuses on the geographical connection or the line represented on a map rather than the physical roadbed.
A linha férrea passa perto da minha casa.
(The railway line passes near my house.)
Eles querem reativar a antiga linha férrea entre as cidades.
(They want to reactivate the old railway line between the cities.)
O trem parou no meio da linha férrea.
(The train stopped in the middle of the railway line.)
Via férrea
C1This is a more technical or physical term regarding the actual track structure (rails, sleepers, and ballast). You use this when talking about construction, maintenance, or the ground the train travels on.
É extremamente perigoso atravessar a via férrea a pé.
(It is extremely dangerous to cross the railway tracks on foot.)
A manutenção da via férrea será realizada durante a madrugada.
(Therefore railway track maintenance will be performed during the early morning.)
Um objeto bloqueou a via férrea e causou atrasos.
(An object blocked the railroad track and caused delays.)
Summary
In short: Ferrovia is the standard word for railway in Brazil, while caminho-de-ferro is the standard in Portugal. Linha férrea usually describes the specific route connecting locations, and via férrea refers to the physical tracks or permanent way, often in technical or safety contexts.