A group of kids have a pillow-fight.
Kids are having a pillow fight
Kids  have a pillow fight is a statement of what is happening.  Kids are having a pillow fight is a first person point of view of what they see happening.
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_have(e1) & n_pillow-fight(x3) & of(x1,x2) & n_kid(x2) & n_group(x1))
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & n_fight(x2) & of(x2,x3) & n_pillow(x3) & n_kid(x1))