Difference between vomiting and excessive spit up?

My little one just got diagnosed with a cow protein intolerance. I have since decided to eliminate dairy from my diet so I can continue to breastfeed her. Our ped prescribed a cream for her the rash on her face and she finally slept. She slept for 9 hours and by the time I went up feed her, she either drank too much or my breastmilk wasn’t agreeing with. I was burping her when so much milk came out. But I can’t tell if it was vomiting of milk or just a lot of spit up? Help!