How about the relative presence or absence of other cannabinoids like THCV?
That post above was the first mention of cbd/thc ratios in this convo. If you read the new McPartland/Small taxonomy paper, you can see they put forward the theory that the variatals from Central Asia, classed as Indica in past, under this new taxonomy classified as ssp. indica var. afghanica/asperrima that states they have a lower THC:CBD ratio, whereas the varietals from South Asia ssp. Indica var. himalayenisis/Indica have a higher ratio.
Personally, I prefer using mixed ratio (3:1, 1:1) flower in evenings for my own use for the sedative effect (couch lock).
If we take the theory that all modern 'hybrid Sativas' that originated from the Sth Asian Indica drug type and were, in recent times classified as 'racy, energetic' then we also assume it is mostly through lack of CBD not just terpene profile.
McPartland/Small also go on to mention terpene profiles stayed relatively consistent between the 4 variatals, which I find interesting.
Its an ongoing debate/exploration and as mentioned in earlier posts and also the paper itself, very muddled from natural and human selection over a millenia.