How can I tell if my pup is playing or fighting the other puppy?

How can I tell if my pup is play fighting or really getting too aggressive? She likes to try to dominate the other puppy by jumping over it's back. I knock her down onto the ground with her stomach up in a submissive stance so she gets the picture that I'm still dominate. Is growling normal when dogs play? I feel so naive.

If the other dog is not objecting, is participating in the play and not running away or yelping in fear or pain, then it's all play. Growling, posturing, jumping on each other and sometimes showing teeth (though eyes wide open and in a silly almost exaggerated way) is all part of it. They often take turns jumping on each other.Stop dominating and let the dogs play. It's perfectly normal and how they learn to relate to each other. You really aren't teaching anything. Only break it up if someone is trying to get away, is unhappy or getting hurt.

They're just playing and doing what they do. They know you're the dominant one. It doesn't mean they won't try to see who's at the bottom. If one gets aggressive the other will let her know. They do growl when they play. Don't interfere unless it gets too rough. But occasionall step in and stop them calmly to let them know that when you say stop they better listen.

Your aggressive dog is letting the other one know she is the boss dog or Alpha dog, Playing and growling is normal.Just make sure she knows you are the boss. //////////////you are the dogs master. She submits to you, thats really good.They will try you out like kids do.