I learned the word «фейерверк», which means fireworks, from a song. But when I use it in conversation with native Russian speakers (my tutors), they correct it to «салют».
Are there any differences? I will accept answers even if it’s just “this particular word is more often used in colloquial speech”.
I'd say that in the common speech, and in terms of fireworks, these two words are practically synonymous, with фейерверк being a bit more formal.
There may be some difference, but it's very subtle. At least to my ear, салют refers only to the fireworks that fly really high (10-20 meters at least), while фейерверк can also refer to smaller types of fireworks (2-3 meters high, or even tabletop). Also, фейерверк may be better suited to the item itself (the pack that you ignite to start fireworks), e.g. to my ear, when you go into a store to buy some fireworks, it's better to say фейерверк — while салют is better for the show itself, or the process of launching them. But maybe that's only me, and others may not see this distinction.
Another, and maybe more important point is that салют is more celebrational, and even commemorative. You wouldn't say «фейерверк в честь чего-то», but «салют в честь чего-то». Conversely, in reference to unintended fireworks (e.g. an ammunition store catching fire with lots of explosions and so on) the word «фейерверк» is more likely to be used to describe what goes on.
Finally, as you may know, the word салют has other meanings that фейерверк does not. It may mean the official military greeting gesture (salute, no relation to fireworks at all), and it may also mean a gun salute, when a gun or cannon is fired to show respect (only tangentially related to fireworks, but may explain how the word салют came to mean fireworks, especially those of a celebrational/commemorative type).
Салют means "military salute", a cannon or rifle discharge to greet or honor a marine vessel, a visiting head of state, a fallen soldier and so on.
In Russia and some of the former Soviet Union republics, cannon salutes are given in most big cities on major military-related holidays such as Victory Day (May 9th), Defender of the Fatherland Day (Feb 23) and its analogs, anniversaries of major WWII battles etc.
Before WWII, blanks were used for military salutes, but as of WWII, firework charges came into use.
In the Soviet Union, fireworks weren't freely available to the general public, and the only time the majority of the Soviet people could see fireworks was in military salutes. So these two words merged in meaning.
There is a difference. In the old days, French was a very popular language amoung the Russian aristocracy and "салют" was initally just a poorly pronounced borrowing of the French word "salut" which meant "greetings," but sounded fancier than just saying it in proper Russian. And even today, the word "салют" is still used on some occasions with a somewhat similar meaning. So when you want to talk about a light show in the sky, a "фейрверк" is just a device you use to create it and the stuff that flies from the ground up, while "салют" is the word for the show itself as a whole with an emphasis on the occasion.
«Салют» has an extra meaning: military greeting. You can use it as an unusual casual greeting.
Otherwise, they have the same meaning.
