What is the difference between these two words? Both mean train. Is there any difference? Are they used in different regions?
Yes there are differences.
火车 literally means "fire car", and it got this name since the steam locomotive era when trains relied on buring coal as fuel. Later this word is generalized to refer to trains. But with modern technology developing, for example 高铁 (High Speed EMU Train), official media usually referes to it as 高铁列车, not 高铁火车. I guess it's because 火车 simply does not fit into the image. 电气列车, 地铁列车 and 轻轨列车 are some other examples.
However, the word 火车 is still used when referring to train in general. For example, 火车票 means "train ticket" and 火车站 means "railway station". You cannot replace 火车 with 列车 in these cases.
Technology aside, 列车 literally means "linked car(s)". So this word should also be used when the subject referred to is related to the linked cars (passenger units), not the locomotive (motor unit). Hence in the word 列车乘务员 (train conductor), you shouldn't use 火车, because the conductor serves the passenger units.
列车 is used more frequently in formal cases. For example, you may often hear such broadcasting in a station:
火车 is more commonly used in daily life. After 2011,
动车 are more and more popular because they are faster and more comfortable than traditional trains, so more and more people are using those two words to replace
火车 and 列车 denote a bit different concepts. The most significant meaning of 列车 is a series of linked train cars. If you are in the depot and see only one single car, you will not call it 列车. In addition, 列车 refers to the tangible object of linked train cars. If you want to tell me you will travel by train, you will not say *坐列车. In contrast, 火车 can refer to the mode of transport. In 火车票 and 火车站 (from Rephinx's examples), 火车 refers to the mode of transport.