If both salicylic acid and acetylsalicylic acid are analgesics, why is acetylsalicylic acid the preferred pain medication

Salicylic Acid also disturbs human stomachs while acetylsalicylic acid doesn't. Isn't that just aspirin?

Salicylic was more commonly used for skin problem such as acne while acetylsalicylic acid also known as aspirin used to treat pain fever

it might share same molecular name but they are not related to each other for molecular function