Railcar

Railcar or Trolley describes any vehicle that uses the Metro rails. They are used by all factions for a variety of means, from transporting goods, people and ammunition, to military use.

Turret Cart
The turret cart appears to be a standard transport for military troops and goods, as well as a war-machine. These railcars are commonly used by the Fourth Reich and appear to be remnants of automobiles fitted for the Metro rails, or simple sections of trains heavily modified for combat. On the top of them is a large operable DShK 12.7mm machinegun which can rotate a full 360 degrees. The turret is very well protected with thick metal and even has functioning spotlights. The front end of the railcar does indeed work like a car, powered via an ignition system and engine.

Hand Cart
Handcarts differ from turret carts in that they're not designed for combat, though many sport sheet metal plates for basic protection from marauding bandits and mutants. They are used primarily by Metro inhabitants for transportation between stations or for moving supplies. Hand carts are most likely old Metro utility vehicles used for servicing the lines - handily, when the bombs fell the hand carts were already in the tunnels and ready for use. Despite their name, can be powered with motors, such as the ones in Depot.

Railbike
The railbike is a rapid on-rails vehicle used by one or two people for quickly navigating the Metro. Judging by the sound it makes, its sidecar and overall seated design it is quite likely that railbikes are built from salvaged motorcycles. The railbike is rather unprotected and not suitable for combat of any kind. The railbike is used by Artyom on numerous occasions in "Black Station", after escaping the Nazis in "Reich" with Pavel and catching up to the Red Line controlled Hansa train in "The Chase". The Nazis also seem to use an armoured version of the Railbike (some can be seen in the level "Trolley Combat" chasing Artyom), in the same role of the Turret Car. The main difference between the two is the size and the position of the turret: while the Turret Car has a Machine Gun in the rear, the armoured Railbike has a Machine Gun in a barbette just next to the driver's seat.

Panzer
The Panzer is a heavily-armoured Reich railcar used primarily to break through enemy positions and destroy smaller railcars with its powerful gun. Little can pierce the thick armour plating surrounding it thus it is both respected and feared in equal measure by the Reich's enemies. The Reich have intentionally built the Panzer to look like a Panzer IV, an iconic tank used by the Third Reich during World War II, to further enhance their Nazi ideology. Artyom faced a Panzer in "Trolley Combat", but lacked any heavy weaponry that could destroy it. Instead he managed to collapse the bridge below it, sending the car plunging into the depths below. A second is seen in "Frontline" though it has already been knocked out by Red troops.

Red Line Tank
The Red Line tank is a heavily armoured railcar, functionally similar to the Panzer, and used for the same reasons as a heavy linebreaker. It carries different armament to the Panzer, firing missiles instead of shells, and has a  DShK 12.7mm machinegun on the rear for warding off infantry. It is, however, less armoured than the Panzer, but no less deadly. However, a lack of armour plating means that critical components are often left unprotected and can be disabled with a high calibre rifle, like the Preved. The tank itself seems to be vulnerable to explosives as it´s destroyable with a Medved. Only two are known to have existed in the Metro. One was part of the second wave of troops attacking the Rangers during the Battle of D6, though Artyom quickly destroyed it, and the other as the final resort in an assault on Frontline in Heavy Squad - this too was destroyed, by Hans.

OSKOM Tank
Several rail tanks were made and used by the OSKOM Rapid Response unit in the Novobirisk Metro. They are encountered in the "Dead City" chapter of Metro Exodus by Artyom and Miller, having been used to defend stations still allied to OSKOM from rioters. They are using slightly modified Panzer models.

Regina
Regina is a special railcar built by Andrew the Blacksmith for the sole purpose of ferrying refugees from the Reich and Red Line to safety in Hansa or neutral stations. It's fairly well armoured, more so than a railbike or even a turret car but not designed for combat, carrying no weapons of any kind. The main dangers it faces are attacks by mutants, the most numerous of which, Spiderbugs, are infesting the tunnels beyond Andrew's home. To ward them off, Regina is outfitted with powerful headlights and lightbulbs, creating a wall of light that no spiderbug will dare go near. While the lights don't ward off other mutants, it does make the gloomy tunnels a little less ominous. Artyom uses Regina to travel to Venice, though he wrecks it before he reaches it, leaving it off its rails. It was mostly intact so it can be presumed Andrew retrieved it and it continued to run refugees back and forth.