A: Marijuana is the name given to cannabis plants that produce high concentrations of delta9 THC and usually low levels of CBD. Delta9 THC is the cannabinoid historically associated with the psychoactive effects of marijuana. 
But now through specialized processing, delta8 THC, delta10 THC, THC-P, THC-O, THC-V, and other naturally occurring cannabinoids can be yielded in high concentrations from CBD extracts. 

These “variations” of THC are each unique but do have similar psychoactive effects to their molecular-cousin, delta9 THC, for most users.