Nicotine polacrilex, also known as nicotine resin complex, consists of nicotine bound to an ion-exchange resin called polacrilex. It is commonly found in nicotine gum and lozenges. When chewed or sucked, the resin slowly releases nicotine into the oral cavity, allowing for gradual absorption through the oral mucosa.

On the other hand, nicotine salt is a form of nicotine that is chemically modified to create a smoother vaping experience. It is typically used in e-liquids for electronic cigarettes. Nicotine salt e-liquids often contain higher concentrations of nicotine compared to traditional freebase nicotine e-liquids, providing a stronger nicotine hit without the harsh throat sensation.