The short answer is that there really isn’t any. Then again, there sure is. It’s confusing, we know, but here’s how it works:
Botanically speaking, hemp and marijuana are the exact same plant. They’re both Cannabis sativa, and when grown for their flowers, which is where all the therapeutic action happens, you probably wouldn’t know which was which.
To tell them apart, you need a lab. That’s because the difference between hemp and marijuana is mostly a legal one based on how much THC a given plant has. (THC, aka tetrahydrocannabinol, is the ingredient in cannabis that’s responsible for marijuana’s high.) If a plant has THC levels of 0.3% or less, it’s classified as hemp. If it’s got more THC than that, it’s labeled marijuana.
Here’s another big difference: Hemp is loaded with CBD but marijuana has almost none.
That’s because, in general, the more THC a cannabis plant contains, the less CBD it will have and vice versa. Today’s marijuana strains, for example, contain around 80 times more THC than CBD while modern hemp has about eight times more CBD than THC on average.
Once upon a time, before people began tinkering with cannabis genetics, the ratio of THC to CBD was closer to 1:1, and there wasn’t much of a distinction between hemp and marijuana. That’s not the case these days. If it’s CBD you’re after (and we are!), you want hemp. If it’s THC you need, you’re looking for medical marijuana.
Some people, of course, want both, and there’s some wisdom in that. Cannabis sativa is an amazing plant containing 66 different cannabinoids. THC and CBD are just the two everyone talks about, but the effects we attribute to them may actually end up being the result of a complicated dance between multiple cannabinoids and/or some of the other 400-plus natural compounds that grow inside both hemp and marijuana.
Time (and a little science!) will tell. For now though, it’s hemp for us and our pets because that’s where the CBD is and the THC isn’t.