Two young boys are climbing over the seat in a vehicle.
Two boys are moving from the back seat of a car to the front seat after simultaneously calling shotgun.
You can not imply the reason why the boys are climbing over the seat. The first sentence doesn't imply that the boys were  simultaneously calling shotgun.
exists e1 s1 x1 x2 x3.(n_seat(x2) & in(e1,x3) & n_vehicle(x3) & over(e1,x2) & Actor(e1,x1) & v_climb(e1) & n_boy(x1) & a_young(s1) & Theme(s1,x1) & card_eq_2(x1))
exists e1 e2 s1 s2 s3 x1 x2 x3 x4.(n_seat(x2) & n_seat(x2) & a_front(s2) & Theme(s2,x2) & a_back(s1) & Theme(s1,x2) & after(e1,e2) & a_simultaneously(s3) & Manner(e2,s3) & Theme(e2,x4) & Actor(e2,x1) & v_call(e2) & n_shotgun(x4) & to(e1,x2) & from(e1,x2) & of(x2,x3) & n_car(x3) & Actor(e1,x1) & v_move(e1) & n_boy(x1) & card_eq_2(x1))