Hemp and marijuana are both Cannabis; they are both variants of the species Cannabis sativa. If you can get high from it, it’s called marijuana and if you can’t it is called hemp.

The difference is whether it contains a significant amount of (THC) tetrahydrocannabinol, which is the compound in the plant that produces euphoria or psychoactive “high”.

For centuries, certain types of cannabis have been bred for the production of fiber, textiles, paper, and food (particularly its protein-rich seeds). This came to be called hemp.

For just as many centuries, other types of cannabis were bred for the production of flower for medicinal purposes, because the flowers of the plant contain much higher concentrations of biochemicals called cannabinoids, such as THC, CBD, and many others. This came to be called marijuana.

In recent decades, cannabis breeders seeking to obtain the plant’s medicinal qualities (particularly CBD) but without the psychoactive “high” (i.e. THC) have been cross-breeding the types of cannabis historically bred for medicinal flower (marijuana) with the types of cannabis historically bred for fiber and textiles, etc. (hemp). This is the origin of the hemp varieties grown today for CBD and other non-psychoactive medicinal qualities.