We don’t know why the fight broke out but we quickly see the style difference between the fighters. In the first 10 seconds of the fight we can see karate kicks and a few boxing punches. There is a weight difference but the smaller girl doesn’t seem to care about her disadvantage.
The woman in jeans has the weight advantage, while the woman in shorts seems to have longer reach. However, the karate stance and the repeated jump kicks keep the distance in favor of the woman in jeans.