CBD

Delta 8 is an entirely synthetic form of THC that is in part derived through hemp.
Therefore it is legal in many of the states that do not allow Marijuana.

Delta 9 is derived through the actual marijuana plant that contains thc. Typically, most delta 9's are not fully synthetic. These are usually allowed in non marijuana states.

I try to steer folks away from delta 8 as it is a synthetic. I don't suggest synthetics for just about anything. Not natural.
I know the scientist who patented and created delta 8.