A boy looks on as a baby laughs.
The boy is making the baby laugh.
Looking at a laughing baby doesn't necessarily mean the boy is making the baby laugh. The cause of the laughing is unknown.
exists e2 e1 x1 x2 x3.(r_on(e1) & as(e1,x2) & Actor(e2,x3) & v_laugh(e2) & (x2 = x3) & n_baby(x2) & Actor(e1,x1) & v_look(e1) & n_boy(x1))
exists e1 x1 x2 x3.(n_laugh(x2) & of(x2,x3) & n_baby(x3) & n_boy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_make(e1))