Lets break it down. CBD, formally known as Cannabidiol, is the second most prevalent of the active ingredients of cannabis (marijuana). While CBD is an essential component of medical marijuana, it is derived directly from the hemp plant, which is a cousin of the marijuana plant. Despite the fact that CBD is a component of marijuana (one of hundreds), by itself, it does not cause a “high"* like THC (tetrahydrocannabinol) does. Both CBD and THC interact in their own ways on different brain receptors and parts of the body. It has been said that CBD may actually lessen the psychoactive effects of THC, depending on the amount of each that has been consumed. (Pretty cool, huh?)
Wait...I'm confused. Are Hemp, Marijuana, and Cannabis the same thing?
Hemp:
Hemp is a specific type of cannabis known scientifically as Cannabis Sativa L. Though they are both part of the same family (and sometimes species), hemp and marijuana have different chemistry and characteristics. Hemp plants contain low levels of the intoxicating phytocannabinoid known as Tetrahydrocannabinol (THC), for which marijuana is well known. However, hemp contains high levels of the non-intoxicating phytocannabinoid Cannabidiol (CBD).
Marijuana:
Marijuana is the intoxicating cousin of hemp. Depending on the taxonomic methods you prefer, marijuana may well be comprised largely of Cannabis Sativa plants as well. And while marijuana and hemp might share a species, they are legally and chemically distinct in a significant way.
Cannabis:
The word Cannabis is a taxonomic term referring to a genus of flowering plants that are members of the family Cannabaceae, which includes about 170 plant species, and contains more than eighty biologically active chemical compounds. The most commonly known compounds are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). CBD is a single compound in the cannabis plant, while marijuana is a type of cannabis plant or plant material that contains THC. The genus is often divided up into three species - Cannabis Sativa, Cannabis Indica, and Cannabis Ruderalis.
Regardless, “cannabis” is actually a broader classification that contains both hemp plants and marijuana plants. At the end of the day, for all their differences, both types of plants are indeed cannabis.**
Citations
*https://www.health.harvard.edu/blog/cannabidiol-cbd-what-we-know-and-what-we-dont-2018082414476
**https://www.prima.co/magazine/what-s-what-hemp-cannabis-and-marijuana/