Well, I do know there is “heavy naptha” and “light naptha”, and just now learned that in some countries naptha can even refer to diesel or gasoline!
I’ve seen a gasoline tank truck go up in flames (series of impressive explosions) — if this was light grade naptha close to gasoline I don’t think I’d want to be anywhere near that tanker...
I think they make a distinction between naptha, fuel oil and diesel, vs crude.
I’m going off of what I’ve seen as far as reports on oil production and how they refer to it, but it could be the russian stuff refers to heavier grades.