Crowd of people hanging out on the stairs.
Some people standing in an office building at a conference.
A crowd is more than some people.  A conference would not be held on the stairs.
exists e1 s1 x1 x2 x3 x4.(n_stair(x4) & a_topic(x1) & of(x1,x2) & a_out(s1) & Manner(e1,s1) & on(e1,x4) & Actor(e1,x3) & v_hang(e1) & (x2 = x3) & n_people(x2) & n_crowd(x1))
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & at(e1,x5) & n_conference(x5) & in(e1,x3) & n_building(x3) & of(x3,x4) & n_office(x4) & Actor(e1,x2) & v_stand(e1) & (x1 = x2) & n_people(x1))