A lot of factors contribute to TH. Yes, nic is one of them, but as SoUnique said the pg/vg ratio and additives (distilled water, pga). Also the coil, wick(s), the voltage and the flavourings used in the juice also contribute to TH. How dry your throat/mouth is also has an effect, so vaping a strong TH juice while having your medium double double will lower the TH because of the cream.