Oh, Yeah. there is a huge difference in body language and vocalisation in mine when they "get it on"
Playfighting is usually on backlegs almost boxing, mouths open, sort of wrestling for best position.
and they sound very growly but they are breathing with it, the sound is coming from their chest.
Real fighting body language is down low, ears back, squinty eyes, and lips drawn back over almost closed teeth.
The sounds are harsh growling from the throat, darting forward snapping at each other. When they engage into the fight it's
frantic, very fast movements as they try to get a "grip" on either the back of the neck or throat.