Elevated railway and Railway system

Elevated railway noun - A railway that is powered by electricity and that runs on a track that is raised above the street level.

Railway system and elevated railway are semantically related. In some cases you can use "Railway system" instead a noun phrase "Elevated railway".

Railway system noun - Line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight.

Elevated railway and railway system are semantically related. Sometimes you can replace phrase "Elevated railway" with "Railway system", this phrases are similar.