The difference between CBN vs CBD is that CBD is a major cannabinoid found in abundance whereas CBN is a minor cannabinoid found in quantities less than 1%. Also, CBN binds with CB receptors unlike CBD which antagonizes CB receptors only in the presence of THC.
While the quantity of CBD is determined by the genetics of the hemp plant, the quantity of CBN depends on the environmental factors since CBN is formed only after the oxidation of THC.
But, CBN and CBD are both therapeutic and effective in promoting restful sleep and relieving pain and inflammation.