Key point is that the epithelial structures, hair follicle and sweat glans are preserved. These structures can go on to re-epithelize without having to graft. Basal layer remains. Deep partial thickness- involves dermis. Basal layer lining appendage remains.
Spontaneous healing can occur but associated with scarring, poor cosmesis and poor functionality.
Entire dermis is devitalized. Wound cannot heal by epithelialization. Dermal blood vessel destroyed. This burn injury has to be grafted. It is dull red, leathery dry.