"Quirium Fuel": A commodity found on the F8 markets screen (if you have installed Fuel Tweaks OXZ).
Can only be purchased if specialised fuel storage containers have been fitted to a ship.
In the Classic Elite game fuel is just fuel! But in the game Manual it became Quirium H-fuel (page 6) and Andy Redman incorporated quirium into his Imprint novel. When Drew Wagar starting writing Oofiction, the science of quirium featured prominently in his Oolite saga as one of his heroes is a scientist working with it. So in the early days the terms Fuel and Quirium were used interchangeably.
Then people started writing OXPs. Commander Frame's Fuel Collector OXP in 2008 led to Phkb's Fuel Tweaks OXP which affected the fuel and the OXP'd version was called Quirium Fuel, a commodity which could be bought and sold. Other people also played around with the concept (Holy Fuel, Quirium Crystals etc).
Hence the peculiar specificity of this page which only deals with the fuel as a commodity.
... when it comes to the difference between Quirium fuel you can scoop or buy on the F8 market page, and the fuel you purchase on the F3 equipment page, the logic I had in my head was that the F8 screen scoopable fuel was a more pure form of the fuel (thus requiring specialised equipment to scoop and specialised tanks for safe transport), while the F3 screen version is less refined/pure, and the impurities result in it being less volatile than the purest form. Phkb (2021)
This list deals with quirium fuel as a commodity - for oxps dealing with fuel (fuel tanks etc, see Quirium)