The cannabdidiol in a phytocannabinoid-rich full-spectrum hemp oil (PCR) is much more effective than a pure cannabidiol isolate, when used at the same level (mg/kg), controlled for the delivery and routes of administration for the following reasons:
(1) Scientific evidence, see references 1-6, exist to show that CBD in the presence of other plant constituents improves the dose-response in a standardized hemp extract, showing it is more potent or efficacious than pure CBD isolate. Various research groups have studied a range of physiological parameters, such as analgesic effects, and have concluded that the higher efficiency of plant extract can be explained by additive or synergistic interactions between CBD, terpenes, and the minor phytocannabinoids or non-cannabinoids presented in the extracts. This is because other phytocannabinoids, including Tetrahydrocannabivarin, Cannabigerol and Cannabichromene, as well as mono- and sesqui-terpenes, exert additional effects of therapeutic interest and the therapeutic synergy observed with plant extracts results in the requirement for a lower amount of active components, with consequent reduced adverse effects.
(2) A full spectrum PCR hemp oil is easier to manufacture with since it can be emulsified, dissolved, and homogenized much more effectively, compared with an isolate. Since the isolates are difficult to dissolve in water-containing media during manufacturing or consumption, they pose a risk of inconsistent delivery of active for consumers and patients alike. Although an insufficient dispersion of isolate in a supplement, vape, or food product is difficult to observe, experimental evidence point to a a better consistency, delivery, and efficiency (bioavailability) when a PCR hemp oil is used to manufacture the finished product.
(3) Isolate CBD has been used for various Investigational New Drug (IND) applications. GW Pharmaceuticals has an approval pending with Food and Drug Administration for a drug with CBD as the active ingredient. Historically, the active ingredients in their purified form are not allowed in any consumer or drug product upon FDA-approval. Therefore, designing a product with purified CBD that will soon be illegal to use, presents a challenge for manufacturers. However, designing consumer products or supplements with full-spectrum hemp oil with up to 80% CBD and no THC provides a solution to those who would want a viable and legal supply of CBD raw material in the form of a botanical extract.
References:  Ruth Gallily, Zhannah Yekhtin, Lumír Ondřej Hanuš, Overcoming the Bell‐Shaped Dose‐Response of Cannabidiol by Using Cannabis Extract Enriched in Cannabidiol, Pharmacology & Pharmacy, 2015, 6, 75‐85