Skytrain is the name of the overall service. Canada Line, Millennium Line, Expo Line and Evergreen Line are the four Skytrain routes. Skytrain is "The Underground" and Canada Line is "Piccadilly Line".

Vancouver's first subway/elevated rail line was built in the 80's and was named Expo Line of the Skytrain system. Expo Line connects the Vancouver waterfront with the cities of New Westminster and Surrey. There was only the one line and it was commonly referred to as Skytrain rather than Expo Line. A second line called Millennium Line was added few years later. It services a more north eastern area but shares some of Expo Line route and platforms. The third Skytrain line, added in 2009, is called Canada Line and runs north and south between downtown Vancouver waterfront and the Vancouver International Airport (YVR). Its train cars are wider and not compatible with the other lines. Canada Line platforms are near Expo and Millennium Line shared platforms, but require some walking to transfer. A fourth line, the east-west Evergreen Line is under construction for completion in 2016.

Many folks interchange the name Skytrain with the various lines which can be confusing. As more lines are added their specific names will become more readily used.