Which characteristic distinguishes a paste from an ointment?

A paste is characterized by its thicker consistency compared to an ointment, making it more viscous and less penetrating. This thicker formulation allows pastes to create a protective barrier on the skin, which can be particularly effective in certain applications, such as in treating skin irritations or rashes. The higher solid content in a paste contributes to this thickness, which is a key distinguishing feature when comparing it to ointments, which typically have a creamier texture and can penetrate the skin more easily due to a different balance of oil and water content.

In contrast, options that suggest being less greasy, made solely of oil, or being alcohol-based do not accurately represent the fundamental differences between pastes and ointments, as both products can vary in greasiness and may involve different compositions not strictly limited to oils or alcohol.