I'm trying to decide if there is any meaningful difference between fuel and propellants. They both seem to cover the same thing, namely the fuel of a spacecraft. I suppose fuel is slightly more generic, as it could include reactive mass for ion drives and the like, but I would rather see propellants and reactive-mass, for instance.
A quick survey of fuel indicates that any question for that tag could easily be covered under propellant. The propellant also seems to include questions that could be covered with fuel.