As piedthepiper mentioned earlier, petroleum distillates are classified by the number of carbon atoms they contain, Cn (where n is the number of atoms) and whether the atoms are aranged in a chain, aliphatic or a ring, aromatic.
Volatility decreases as C increases but the amount of energy per molecule increases so propane (C3) is a gas but Octane (C8) is a liquid at room temperature. One molecule of octane releases almost 2.5 times more energy when burnt than a molecule of propane. Aromatic molecules contain more energy and are less volatile than the equivalent aliphatic molecule.
Kerosene (sold as Paraffin in the UK) is typically C6-C16
Naphtha (light) C5-C6
Naphtha (heavy) (C6-C12) so it consilts of the lighter distillates of kerosene
From the Safety Data Sheet, Redex is 95% heavy naphtha or it's derivatives but you could still label it as kerosene.
The B&Q Terpentine Substitute is heavy naphtha but labelled as Cn content.
White spirit is C7-C12 so again heavy naphtha based with up to 25% aromatic content. Aromatics don't combust as completely as Aliphatics so I'd be less inclined to put this in my engine.
What they all have in common is they're excellent organic solvents i.e. they desolve carbon deposits.
Hope this helps, and yes, I am a Chemist