THC and THCA are two different chemical compounds found in the cannabis plant. THC is the psychoactive compound that produces the "high" associated with marijuana use, while THCA is a non-psychoactive precursor to THC that requires heat to convert into THC. THCA is the acidic, non-psychoactive form of THC found in raw, unheated cannabis, while THC is the psychoactive form of the compound that results from heating or aging cannabis. THC is responsible for the characteristic "high" associated with marijuana use, while THCA does not have psychoactive effects. THCA molecules, on the other hand, do not produce the psychoactive effects of THC. However, it may have potential medical benefits such as anti-inflammatory and neuroprotective properties. In summary, THC is the psychoactive compound that produces the "high" associated with marijuana use, while THCA is a non-psychoactive precursor to THC that requires heat to convert into THC.