Regurgitation looks just like when the cockbird is feeding either babies or hen. They are bringing it up into their throat to feed others. They arch their head and neck and then bob their heads up and down to bring the food up. Regurgitation is an up and down movement. This is a normal behavior. Read more: Why does my budgie regurgitate for me (or another object)?
Vomiting is a bit stronger like convulsive and the bird shakes it head side to side and splatters the vomit. Vomiting is a sideways shaking of the head. If your bird if vomiting you need to call your Avian Vet immediately this is a sign of sickness.