I think in modern day Japan 電車 refers to all trains. At least that's my impression from discussing it with my Japanese fiancée. I think more accurately, different terms were used in the past but now でんしゃ is the common word for train, rather than an electric train specifically.
However, the difference is trivial now that the vast majority of trains operating in Japan are electric. They will be more specific for the service they are travelling on such as subway, JR, and high speed services 新幹線「しんかんせん」(known as "bullet train" in English).
Note that Japanese people tend to refer to the company or service offered rather than the physical train. It's basically assumed you will travel by train unless you specify driving or flying. They have JR lines, subway, and metro lines running underground. That's not a typo: Tokyo has both Metro and Subway lines, depending on the company operating the lines. It is not a matter or whether you use "Subway" or "Metro" if you are American or European. You will be referring to different specific lines in Tokyo as several companies operate there.
This does appear to be the case, and a steam train should be 汽車 (which, confusingly, means a car in Chinese). You should perhaps report the image (unless any natives come forward to say that 電車 is commonly used to refer to any type of train, which is also possible) .
As the dictionary 新明解 defines, a 電車 is (a train composed of) wagon(s) with equipments that uses electricity to go on rails.
> 電車 電力でレールの上を走る装置が付いている車両（から成る列車）。
Natives might say that 電車 is also used to refer to any type of train, but it is not more than colloquial.