There is a lot of play-fighting around here. Lily generally starts it by taunting Tinsel in some fashion: dive-bombing her from the top of the couch, smacking her on the head, or blocking Tinsel's path, as she was doing here. You can see that she has her sweet back feet positioned against the wall so that she can push her heavy little body directly in front of Tinsel, not unlike a slow-moving missile. You can tell from Tinsel's ear position that she's irritated!
What follows is a lot of growling, head smacking, and chasing. I will say that Lily never snarls or uses her claws on Tinsel, who was front-declawed when we adopted her. They each do "pretend biting" but never touch the other with their teeth.
Even though this play-fighting sounds and looks scary, I think it's all in fun. And as much as Lily drives Tinsel crazy, I think she secretly enjoys having an irritating little sister around the house.