Let us start by saying that there are definitely individuals and companies that use some of these different terms interchangeably - and that the difference is really something that should be investigated by the consumer. There are many different schools of thought, and certainly some mis-information that is either intentionally or mistakenly placed about. We are all in a learning curve when it comes to the world of cannabis, and what this plant brings for human health.
We have written before about the difference between marijuana and hemp. It is important to note, however, that all of these products do come from the cannabis plant. So marijuana is not the same as hemp, however, both hemp and marijuana are a form of cannabis.
This information comes from our own gathering of various resources, and is open to the debate and interpretation of others, who may see and find nuances in what they consider correct. However, we hope to bring more information to the table, to help you do your own research and find out what is best for you as a supplement or a treatment option.
In the broadest sense of the word, this could theoretically mean any oil coming from any cannabis plant. Now, some strains of cannabis are bred for high levels of the psychoactive cannabinoid THC (Tetrahydrocannabinol) and some strains of cannabis have virtually no THC and instead are high in other cannabinoid content - like that of CBD (Cannabidiol). Marijuana is a type of cannabis that has high levels of THC and gets people "high". Hemp is a type of cannabis that has high levels of CBD, and does not give people the "high", but instead may offer some medicinal benefits. If someone uses the term "cannabis oil", unless it is specified what they mean, then this could be oil made from any type of cannabis plant - either marijuana, hemp, or otherwise - and so people should exercise caution when investigating or purchasing products that do not specify what the company is using or what the company means. Also, be wary of media using this term, as it may be used incorrectly when reporting on the legal or illegal nature of cannabis products.
This is oil refined from the marijuana species of cannabis. It is psychoactive, and has various levels of the cannabinoid THC. Marijuana oil would only be "legal" for use in the States that have approved using marijuana recreationally (Colorado, Alaska, Washington, Oregon), or the 23 and counting States that have passed "Medical Marijuana" laws that do allow access for patients to use marijuana as a form of treatment for sickness and disease.
Hemp oil is generally referred to as oil that is made from the actual seeds of the hemp plant. Hemp oil in this regard has mainly topical applications - especially used in soaps, lotions, and shampoos/conditioners. Hemp seeds that are not refined into oil are available to consume just by themselves (they are quite delicious in our opinion), and hemp seeds can also be ground into powder - to use in protein drinks, baking, etc. There is virtually no THC (the psychoactive cannabinoid in the marijuana species of plant), and hemp oil products are legal to purchase and sell in all 50 States (and have been for decades).
CBD stand for Cannabidiol - a cannabinoid found in high levels in hemp. CBD is not psychoactive, and there is preliminary research showing many potential benefits to human health. Each human being is "pre-wired" with an Endocannabinoid System, and we have "receptors" in our body that recognize the various cannabinoids. Most pharmaceutical drugs are artificially synthesized to "fool" our receptors - however, cannabinoids are already understood and accepted by a human's Endocannabinoid System. CBD oil is refined from the hemp flowers, leaves, and stalks (versus the seeds like in regular hemp oil). CBD Oil can be used both internally and topically. CBD Oil is legal to purchase and sell in all 50 States, and can be used as a supplement.
CBD Oil that also has THC: There are some CBD oils that are not legal to buy and sell in all 50 States. These CBD products have the addition of THC (the psychoactive cannabinoid), but are sometimes referred to as simply 'CBD oil" (especially by the media, which fails to explain why that particular type of CBD oil is "illegal" - because it also has marijuana and THC in it). If CBD oil is referred to as "illegal" or a "banned substance", then this is CBD oil that has THC in it and actually comes from marijuana - not hemp.
CBD Oil that contains no THC and that can be taken as a supplement is legal to purchase and sell in all 50 States, and that is the only reason that Google and Amazon allow such on their large national marketplaces. These products are legal to purchase and sell because of their absence of the psychoactive component THC.