Given that vaseline has fewer components, it might be preferable. Since Vaseline is also flavorless and odorless, it might be preferable if you typically react to different substances. Both form a barrier to prevent dry air from absorbing the moisture from the lips. The primary difference between the two is in the components. Several flavors, scents, and variants of chapstick can irritate your lips. There could be allergens in some chapstick that could result in an allergic reaction. You might be tempted to keep chewing on the chapstick due to its many flavors, which could gradually become an addiction. If you only apply a thin layer of vaseline, you won't experience the same problems.