A group of people are standing at a concert.
People are rocking out.
Sentence 1 explains that the people are just standing at the concert. You cannot tell that they are rocking out from the information given.
exists e1 x1 x2 x3.(at(e1,x3) & n_concert(x3) & Actor(e1,x1) & v_stand(e1) & of(x1,x2) & n_people(x2) & n_group(x1))
exists e1 s1 x1.(a_out(s1) & Manner(e1,s1) & Actor(e1,x1) & v_rock(e1) & n_people(x1))