When a dog is playing, it often shows signs of excitement and enjoyment. It may wag its tail vigorously, bounce around, and make playful noises such as grunting or barking. In addition, a dog may initiate playful behavior by bringing you toys or nudging you to play.
On the other hand, when a dog is being aggressive, it may show signs of growling, baring its teeth, and standing stiffly with a raised tail. It may also snap or lunge at you or other animals.
It is important to remember that dogs have different levels of playfulness and there may be some overlap between playful behavior and aggression. For example, a dog that is playing may bite your hand or arm gently, but a dog that is being aggressive may bite down hard and not let go.
To determine whether your dog is playing or being aggressive, it is important to look at its body language and assess the context of the situation. If you are unsure, it may be best to consult a professional dog trainer or behaviorist. They can help you identify the signs of play and aggression and provide guidance on how to respond to each behavior.