“I’m not some mob boss,” Ms. Wazwaz said in an interview. “I’m a soccer mom with kids.”

Confusion over CBD dates back years, but it intensified last year when a provision of the 2018 Farm Bill lifted a federal ban on hemp production that had previously classified hemp as a controlled substance on a par with heroin.

Both hemp and marijuana are varieties of the cannabis plant, which is believed to have been among the first plants that humans cultivated. The plants produce a family of chemicals known as cannabinoids, some of which are psychoactive — meaning they produce a high when smoked or ingested — while others are not. A major difference between marijuana and hemp lies in how much of each they produce.

Marijuana is rich in THC, or tetrahydrocannabinol, the psychoactive component; it can account for as much as 40 percent of the total cannabinoid content. Hemp, on the other hand, is richer in CBD, and generally contains only 0.3 percent THC or less. CBD oils, which are processed from the hemp plant, are legal to possess under the new federal law as long as they, too, contain no more than 0.3 percent THC.

Most states, though, have yet to change their laws to match the new federal rules, leaving local police and prosecutors in a quandary over what is legal and what is not. The result has been a gold rush of CBD marketers, a raft of online ruminations about what is permissible, and, increasingly, confusion.