A dog uses the “play bow” stance to initiate playtime, but since cats do not use such posturing, they may process this as a threatening lunge and become defensive, thus confusing the dog.
A cat shows affection by nuzzling up to an object of affection but for a dog pushiness can indicate dominance or possession.
Tail positioning is different too. For dogs, a tail held high and moving quickly can mean aggression or excitement and a level relaxed tail can mean calmness and friendship. But for a cat it’s the opposite. A tail held high can signal friendship, while a lowered tail can signal trouble.
Dogs and cats, ultimately, despite their differences can and do learn to live peacefully together, which is genuinely a credit to them to overcome such instinctive obstacles.