i think oderless mineral spirits is 99% hexane. let me check according to wiki:
"A typical composition for mineral spirits is the following: aliphatic solvent hexane having a maximum aromatic hydrocarbon content of 0.1% by volume, a kauri-butanol value of 29, an initial boiling point of 149 °F (65 °C), a dry point of approximately 156 °F (69 °C), and a specific mass of 0.7 g/cc. In the European Community, the composition of mineral spirits comes from Article 11(2) of Directive 2002/96/EC (WEEE)."
so its mostly hexane. the thing with naptha is it contains many aromatic hydrocarbons like toluene probably benzene which are a bit tougher to evaporate and more toxic. its a substitute for turpentine so painters can feel better about the solvents they are inhaling its available all over.