Updated: Aug 17, 2020
Hemp and marijuana is the same plant; they are different names for the same genus (Cannabis Sativa) and species.
The difference is that hemp plants contain no more than 0.3 percent (by dry weight) of delta THC (tetrahydrocannabinol), the psychoactive substance found in marijuana.
In other words, Cannabis plants with 0.3 percent or less of THC are hemp. Cannabis plants with more than 0.3 percent delta THC are marijuana.