Tall oil fatty acids are a byproduct of the kraft pulping process for softwood, consisting mainly of oleic and linoleic acids with rosin acid impurities. They are classified separately from stearic and oleic acids because of their distinct origin and composition. Stearic acid (382311) and oleic acid (382312) are typically derived from animal or vegetable fats by hydrolysis and fractionation, yielding purer, more defined products.

Fatty alcohols are the reduced form of fatty acids—the carboxylic acid group has been hydrogenated to a primary alcohol (e.g., lauryl, cetyl, or stearyl alcohol). They are used as emollients, emulsifiers, and surfactant intermediates rather than as acidic reactants. Both groups appear in heading 3823 because they share a common oleochemical origin, but their chemical function and downstream applications differ substantially.