According to The Definitive Guide To Kraata & Rahkshi, as well as Makuta’s Guide To The Universe, Limited Invulnerability only protects from physical damage, while Ice Resistance and Fire Resistance protect from extreme temperatures.
Minor correction, but to be clear, the Kraata chart says Level 6 is “absolutely invulnerable to physical harm of any kind,” while Makuta’s Guide says it’s “invulnerable to physical harm from most attacks.”
But limited invulnerability says it can resist those as well. At stage 3 it says limited resistance to fire and ice, at stage 4 it says immune to environmental extremes which should include volcanic and arctic areas, and at stage 5 it says resist the elemental powers of the toa Nuva which include fire and ice. So I ask once again how is fire and ice resistance not matched by limited invulnerability what are those 2 kraata powers better at in some application that limited invulnerability is not?