How are marijuana, cannabis and hemp different? A guide to weed terms.

The cannabis plant and its many products come with a complicated and sometimes confusing vocabulary. Many words are used interchangeably, but there are some key differences.

We interviewed experts to compile this guide to explain what these words mean — and what the science says.

Cannabis usually refers to the plant from which various weed products come. Both scientists and cannabis industry professionals use the term.

In the United States, the term marijuana refers to cannabis plants that have a certain level of tetrahydrocannabinol (THC). THC is responsible for getting people high. Marijuana is legal in some states but illegal federally.

Other countries, however, rarely use the word and call anything with high THC cannabis. Some U.S. lawmakers have also pushed to abandon the use of the word marijuana, arguing it has racist roots.

Pot, mary jane, dope and kush are slang words used to refer to marijuana.

Hemp is cannabis plants that don’t have high levels of THC. Hemp is used primarily for commercial and industrial products such as rope, clothing and even food. It’s legal across the United States.

These are a group of compounds unique to the cannabis plant. The two most popular cannabinoids are probably familiar to most people: THC and cannabidiol, commonly referred to as CBD.

There are other minor cannabinoids that are integrated into products on the market. Many dispensaries tout that cannabinol (CBN) can help improve sleep, and cannabigerol (CBG) reduces pain, but experts are skeptical.

Some of these minor cannabinoids have been studied in mice, but there have not been many rigorous studies in humans, said Shanna Babalonis, the director of the UK Cannabis Center at the University of Kentucky.

THC is the primary psychoactive compound from the cannabis plant.

It’s what accounts for the typical weed high, and studies suggest there is a risk of dependence if used often. The most common type of THC is delta-9 THC.

The second-most prevalent cannabinoid in the plant, CBD is still psychoactive but doesn’t have the same intoxicating effects as THC. Many users report that its more mild effects help mediate pain and regulate anxiety.

According to the World Health Organization, it also has a relatively low or no abuse potential. “We don’t think people will have a problem with drug abuse with CBD,” Babalonis said.

CBD products are legal in the United States, as long as they don’t have more than a certain amount of THC.

Products with delta-8 tetrahydrocannabinol (or delta-8) have been popping up in headshops, gas stations and dispensaries across the country. It exists in the cannabis plant in trace amounts and has the same elements as THC.

Many users report its effects as somewhere between regular THC and CBD. It’s also somewhat legal thanks to a loophole that permits products derived from hemp to be sold — which applies to most delta-8 on the market.

In the industry, flower or bud is used to refer to the part of the dried cannabis plant that can be smoked.

Monique McHenry, director of the Medical Cannabis Center for Research and Education at the University of Vermont, says, scientifically, a flower is the reproductive part of a plant and a bud is a young development on a plant.

When buying weed, you will be inundated with fun strain names such as “Bubba Kush,” “Girl Scout Cookies” and “Pineapple Express.” This is the industry’s way of differentiating between products, but there’s little science behind it.

“People use these names all over the place but they’re not identifying unique genetic identities or strains like people think they might be,” said Sean Myles an associate professor in agriculture at Dalhousie University.

Most cannabis products are labeled as either sativa or indica to help guide consumers on what kind of high they want. Users report that sativa is more uplifting, whereas indica is often described as more relaxing. The anecdotal evidence about differences in indica and sativa have not been supported by science.

The two are distinct species of cannabis, but experts say there aren’t genetic differences between what’s on the market. “If you look at the chemicals, they don’t consistently fall into groups that the market labels sativa or indica,” McHenry said.

Dispensaries also sell products that they say are a mix of both sativa and indica — but experts say this is more of an industry label than anything else.

Many weed products now boast of various terpenes on their labels. These are naturally occurring in the plant and account for the difference in weed smells.

For instance, strains that have terpenes with fruity aromas are often described as “lemon” or “strawberry,” while strains with earthy terpenes might be described as “diesel” or “funky,” Myles said.

A cigarette, but with cannabis flower. Those with tobacco are called spliffs.

An emptied cigar filled with cannabis.

A small basin — usually glass — used for smoking cannabis flower.

A glass water pipe. It can be used for cannabis but also tobacco.

These are cannabis products that can be consumed. Brownies are a common example, but there are many other sweet (and salty) edibles.

Named for their resemblance to pens, weed pens are used to inhale cannabis and come in two types. Dab pens are specifically for concentrated cannabis products such as wax, shatter and rosin. With vape pens, you’re vaping either flower or cannabis oil cartridges, often called carts.

This is a cannabis extract that can also be consumed but is usually faster-acting than edibles, as users will swallow or absorb it under the tongue.