Without any knowledge of the individual circumstance, I would say in the absence of documentation, any coils that come with a
tank (RTA, RDTA, whatever) are Kanthal.
Here, how are you calculating that value to suggest it's 0.05 ohm less? Just gauge and wraps? There are lots of other variables from the ID not being exactly what you think it is to the lengths of the legs that a 0.05 ohm difference from say Steam Engine vs. even a coil I made myself wouldn't raise any concern that something is off. Off by 0.25 ohm, yes, something is amiss. Regardless, stick to wattage and enjoy. What's the new tank?