A hockey player guards the goal.
A goalie does his job
Not all hockey players are a goalie.
exists e1 x1 x2 x3.(n_goal(x3) & Theme(e1,x3) & Actor(e1,x1) & v_guard(e1) & n_player(x1) & of(x1,x2) & n_hockey(x2))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_job(x2) & of(x2,x1) & n_male(x1) & n_goalie(x1))