quite simple.
tefzel (Dupont trademark, generic = ETFE) is self extenguishing if it ever catches fire.
Tefzel is rated at 150 degree celsius for CONTINOUS use. That is a whopping 302 degree fahrenheit. Hence why they can use a smaller gauge for the same amount of current. Also is why aircraft use this wiring.
Tefzel smokes minimally when it catches fire.
Spec55 is almost the same as tefzel except it has a higher operating temprature. Both (Tefzel and spec 55) meet and exceed MIL-W-22759/16 and MIL-W-22759/18. Spec 55 wiring is good to 200 degree celcius (392 degree fahrenhiet).
Very flexible. Very light. All the f-1 teams use this wiring.