Denatured alcohol is always adulterated ethanol, another name is ruined high proof vodka. It is 'denatured' with toxins, usually methanol or
wood alcohol, hence the name methylated spirits. Isopropyl alcohol, also called isopropanol, is sold unmixed or 'un-denatured' as it is somewhat
toxic by itself and not regarded by the feds as drinkable, and hence not taxed separately as are alcoholic drinks which are all flavored ethanol
in concentrations under 60% (except "grain' alcohol which is ~95%). Rubbing alcohol can be either isopropyl or denatured ethanol but is usually isopropyl.
From a solvent/fuel pov they are the same.