What is TFN?
What Makes It Different?
Molecularly the nicotine in both are the same. This does not mean TFN is just nicotine adjacent, it is authentic nicotine.
When farm harvested tobacco has the nicotine pulled from it, the process brings out impurities from the product. Like the residual plant matter or the taste and smell of the solvent used to strip the nicotine.
Nicotine, when usually completely neutral in taste and odor, can be tainted by the chemicals causing its pungent and repulsive odor. With a pure nicotine substitute you get none of these issues, meaning its perfect for E-juices. TFN E-liquids presents a smooth hit and spectacular flavor. This is the main reason for TFN's rise in popularity, certainly attributed to the details listed above, despite its manufacturing cost.
Safety Concerns
As far as comparing the two, they are on the same level. As aforementioned they are molecularly the same, so body wise you wont be able to tell a difference.
A few studies have said TFN is safer due to the lack of impurities like the carcinogens involved, so if that's something you're trying to avoid when vaping then TFN is your best bet.