The key difference between isopropyl alcohol and denatured alcohol is that the isopropyl alcohol has three carbon atoms whereas the denatured alcohol mainly contains ethanol, which has two carbon atoms.
Isopropyl alcohol and denatured alcohol falls under the category of alcohol since they have a –OH group. The OH group is attached to an sp3 hybridized carbon. Furthermore, these are the smaller alcohols in the series with two or three carbons. Also, both are polar liquids and have the capability to form hydrogen bonds. Therefore, both have somewhat similar physical and chemical properties. For example, both are flammable and toxic liquids.