Simple answer:
No. Hemp and marijuana are very similar but differ in a significant way. Hemp plants are very low in THC and can have no more than 0.3% THC as defined by law. Marijuana plants have higher levels of THC, anywhere from 5-30%. Even if a hemp plant goes over this 0.3% legal limit it will never go past roughly 1% THC. (Keep in mind that technically any cannabis plant that exceeds 0.3% THC is considered marijuana by the federal government). Hemp and Marijuana are both in the same family of plants called Cannabaceae and the same genus, Cannabis L. Many people incorrectly use the word “Cannabis” to describe marijuana. When we refer to Cannabis we are talking about the whole genus, including both hemp and marijuana.
For a more thorough answer see below:
Federal law defines hemp and marijuana using the 0.3% THC limit as a distinction. This definition is helpful, but if we look at the science, we can see that the reality is a bit more complicated. Hemp and marijuana are different in that they consist of different “Chemo types” (or “chemo-vars”). As in, they differ in chemical composition. Marijuana is THC dominant and contains THC concentrations anywhere from 5-30%. Marijuana is considered a “Type I” chemo type. Hemp plants are CBD dominant containing CBD concentrations anywhere from 5-25% and THC concentrations anywhere from 0-1%. Hemp is considered a “Type III” chemo type. Even if a hemp plant goes over this 0.3% legal limit it will never go past roughly 1% THC because the enzyme required for THC to be synthesized (THCA-synthase) is not present or functional in traditional low THC hemp plants.5
There are cannabis plants that have high levels of both THC and CBD. These are considered “Type II” chemo types. There are also CBG dominant plants that are considered “Type IV” chemo types and cannabis plants with little to no cannabinoids of any kind that are considered “Type V” chemo types. Any cannabis plant, whether hemp or marijuana, regardless of chemo type, that goes over 0.3% THC is considered marijuana by federal law and not hemp.
For further reading about chemo types and THC-A/CBD-A synthase enzymes see: SNP in Potentially Defunct Tetrahydrocannabinolic Acid Synthase Is a Marker for Cannabigerolic Acid Dominance in Cannabis sativa L. 5