Nicotine bitartrate dihydrate is a crystalline salt form of nicotine combined with tartaric acid. It is often used in pharmaceutical formulations and research applications due to its stability and solubility characteristics. Nicotine bitartrate dihydrate is commonly used in nicotine replacement therapy (NRT) products and smoking cessation medications.

On the other hand, nicotine polacrilex is a resin complex of nicotine bound to an ion-exchange resin, often in a gum or lozenge form. It is used primarily in nicotine replacement therapy products such as nicotine gum and nicotine lozenges. Nicotine polacrilex slowly releases nicotine when chewed or dissolved in the mouth, providing a controlled release to help manage nicotine withdrawal symptoms.