A snowboarder going over a cliff.
A person is doing tricks with friends while snowboarding.
The first sentence just tells us that the snowboarder goes off the cliff and nothing about him doing tricks or that he was with friends.
exists e1 x1 x2 x3.(a_topic(x1) & over(e1,x3) & n_cliff(x3) & Actor(e1,x2) & v_go(e1) & (x1 = x2) & n_snowboarder(x1))
exists e1 e2 x1 x2 x3.(while(e1,e2) & Actor(e2,x1) & v_snowboard(e2) & with(e1,x3) & n_friend(x3) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_trick(x2) & n_person(x1))