Im confused on the difference, if there is a difference.
Botanical implies that the terpenes were extracted from plants.
Food grade implies that they meet all the FDA and/or USDA requirements to be safe for consumption. This is a purity standard, not a standard on derivation or where they came from.
It would be possible for food grade terpenes to not have come from plant extraction - they could have been synthesized but still meet the purity standard to be food grade.
Hope that helps.
Botanical can also imply that in the case of cannabis, that the terpenes were derived from sources other than cannabis.
Also, cannabis/hemp terpenes are not classifiable a food grade (currently). So if something has a food grade certificate then it is inherently not cannabis/hemp derived. Food grade means very little in this context.