Cannabis is the genus name used to identify a type of flowering plant that includes marijuana and hemp. Marijuana and hemp are both part of the Cannabis Genus, yet they are different. Similar to how oranges and limes are both considered Citrus fruits, but look and taste differently.
Marijuana plants are high in THC, the chemical compound that causes psychoactive effects. Marijuana that contains THC is typically used by adults for medical or recreational purposes.
Hemp plants are low in THC and high in Cannabidiol, or CBD. CBD is non-psychoactive and safe to use for medicinal purposes.