What's the difference between marijuana, cannabis? 4/20 terms to know.

Marijuana − medical and recreational − is legal throughout more than half of the United States, and for some looking to familiarize themselves with the plant and its effects, learning all of the associated terminology may feel daunting.

There's marijuana, cannabis, hemp and then there's Delta 8, 9 and 10. What are the differences, and what should new (and even veteran) users know before toking up?

As the unofficial weed holiday 4/20 (April 20) rolls around − no pun intended − here are some key pot terms to be familiar with.

Marijuana encompasses a broad range of products derived from the Cannabis sativa plant that contain the highest levels of tetrahydrocannabinol, more commonly known as THC.

Consuming marijuana, whether that be by smoking it, eating it in edible form or drinking it as a tincture, can have intoxicating effects and can trigger changes in mood or thoughts.

Under U.S. federal law, marijuana is classified as a Schedule I drug. This category also includes heroin, LSD, methamphetamines and peyote.

Marijuana was classified as a Schedule 1 drug with the establishment of the Controlled Substances Act in 1970.

Despite often being used interchangeably, marijuana and cannabis are not the same.

Cannabis refers to all of the products derived from the Cannabis sativa plant, according to the National Center for Complementary and Integrative Health. Marijuana refers to the specific products from the Cannabis sativa plant that contain substantial amounts of THC.

Tetrahydrocannabinol is the substance found within the Cannabis sativa plant that is primarily responsible for marijuana's psychological effects on a user.

Cannabinoids are the different chemicals found within the Cannabis sativa plant. There are more than 100 cannabinoids, according to the Alcohol and Drug Foundation, but the most common are THC and cannabidiol, or CBD.

Cannabidiol, more commonly known as CBD, is a chemical compound that can be found in both the Cannabis sativa and hemp plants. Under U.S. federal law, CBD is legal.

CBD does not contain THC, so it is not impairing, meaning it does not cause a user to get "high," or have psychoactive effects, according to the Centers for Disease Control and Prevention (CDC).

To date, the Food and Drug Administration has only approved one CBD product, a prescription oil called Epidiolex, which is used to treat seizures.

Delta 8, Delta 9 and Delta 10 are three of the more than 100 cannabinoids that exist.

Under federal law, Delta 8 and Delta 10 are legal for consumer purchase and usage. Delta 9 is not legal under federal law. States are permitted to write their own legislation about Delta 9 possession, consumption and distribution. Debates about the legalization of medical and recreational marijuana largely revolve around Delta 9.

Delta 9 is the most abundant form of THC found in the Cannabis sativa plant, according to Healthline. Delta 9 also produces the most psychoactive effects and can be used for a variety of reasons, including to help with anxiety, insomnia, low appetite, muscle pain and nausea.

Delta 8 and Delta 10 are both extracted from hemp-derived CBD.

Often referred to as "marijuana-lite" or "diet weed," Delta 8 is commonly used to calm nausea, boost appetite, ease pain, boost mental health and prevent vomiting during cancer treatments, according to WebMD.

Delta 10 has a lower THC potency than Delta 8 or Delta 9, meaning users typically experience less psychoactive effects.

All three cannabinoids can show up on a drug test.

Synthetic marijuana is lab-made marijuana and may be referred to as "Spice" or "K2." Synthetic marijuana is often sprayed onto dried plant material to make it smokeable. It can also be sold as a liquid to use in vapes.

Over the years, the federal government has banned several different types of synthetic marijuana, as the lab-made products can lead to severe illness and even death. Negative symptoms may include irritability, confusion, hallucinations, seizures, sleepiness, breathing problems, heart attacks, kidney failure and muscle damage, according to the CDC.

Because synthetic marijuana isn't regulated, there are no standards for its production, packaging or selling.

Cannabinol, or CBN, is a different type of cannabinoid found in the Cannabis sativa plant. When THC components break down, a less potent cannabinoid called CBN emerges, according to WebMD. CBN is about 25% as effective as THC. Less research has been done on CBN, but it does contain more THC than CBD, so it can produce mild psychoactive effects. CBN is largely used to relieve sleeping conditions like insomnia, WebMD states.

Marijuana and hemp can be used interchangeably, as they are the same species, according to Healthline. The difference comes from the amount of THC they both contain.

Healthline reports that hemp contains 0.3% or less THC by dry weight, so because the THC level is so low, it is unlikely that a user will get high.

Hemp, in addition to its medical and beauty uses, can also be used for commercial and industrial purposes, like rope, clothing, paper, bioplastics and biofuel.

Hashish, more commonly referred to as just "hash," is made from the resin of the Cannabis sativa plant. It is typically dried and pressed into blocks to be smoked or eaten, according to Partnership to End Addiction.

Edibles are marijuana-infused products that a user can eat or drink. Cookies, cakes, brownies, gummy candies and soft drinks are common edibles.

Editor's note: This story has been updated to fix a typo.

Greta Cross is a national trending reporter at USA TODAY. Story idea? Email her at gcross@usatoday.com.