A resistance wire (R) heats up when a current is sent through it. A non resistance (NR) wire doesn't.
Uaually 1 piece of R and 2 pieces of NR wires are joined together with R wire wrapped or coiled around a wick which is saturated with
eliquid. The NR wires creates a path from the positive and negative poles.
When a current is applied, only the R wire will heat up, vapourising the liquid.