Hemp and cannabis
Both are Cannabis sativa; the difference is in the cultivar and in the law.
Hemp and cannabis are the same botanical species, Cannabis sativa. The distinction is not botanical but agricultural and legal.
"Hemp" generally refers to cultivars low in THC, grown for fibre, seed or CBD. Other cultivars have been bred over decades for higher THC, and for colour, aroma and resin content.
By the early twentieth century hemp was classed among the world's principal industrial fibre plants alongside jute, flax and manila — a classification that held until cultivation declined in the West mid-century.