The main differences lie in solubility, absorption, and serving size:
Creatine Monohydrate: The most extensively researched and proven form of creatine in the world. It requires a standard daily dose of 5g and can occasionally cause minor water retention.
Creatine HCL (Hydrochloride): Molecularly bound with hydrochloric acid to drastically improve water solubility. Because it is absorbed more efficiently by the body, it requires a much smaller daily serving size and is less likely to cause digestive issues or bloating.