Yeah RER (here A, but most RER lines have at least some double deckers in their rolling stock) in Paris is a commuter train, however it has several stations inside Paris itself, usually in some important hubs (train stations and other large railway stations)
However it must be noted, like other commenters said in the thread, that the frequency is completely different. Many lines in Paris can reach a peak frequency of a subway every 2 mins or so. RER is at most one every five minutes, probably more though (inside the city and regardless of the destination, so for a specific destination, frequency is lower)
But yeah, it doesn’t really serve the same purpose as subway
Yeah RER (here A, but most RER lines have at least some double deckers in their rolling stock) in Paris is a commuter train, however it has several stations inside Paris itself, usually in some important hubs (train stations and other large railway stations)
However it must be noted, like other commenters said in the thread, that the frequency is completely different. Many lines in Paris can reach a peak frequency of a subway every 2 mins or so. RER is at most one every five minutes, probably more though (inside the city and regardless of the destination, so for a specific destination, frequency is lower)
But yeah, it doesn’t really serve the same purpose as subway