A balm is a combination of butters, oils and waxes used in skincare as the base to which essential oils or other active ingredients are added. Creams have similar ingredients, however, they also contain water. This means that they need preservatives as an anti-microbial to avoid the cream from going off, unlike balms, which do not contain water so No Chemical Preservatives
Strictly speaking a balm is anything that heals, soothes, or mitigates pain and closely related to the word ointment An ointment tends to be a semi solid or oily medicated formulation applied to the skin to heal or protect. So there can be a cross over between the two. Salves are designed to reduce inflammation and soreness by soothing properties.