Two people in black hats are standing behind a counter.
two people in hats are standing behind a counter serving lunch.
The first sentence says nothing about what time of day it is or what is being served; so, lunch or any other meal cannot be said to be going on based on the information in sentence 1.
exists e1 s1 x1 x2 x3.(behind(e1,x3) & n_counter(x3) & Actor(e1,x1) & v_stand(e1) & in(x1,x2) & n_hat(x2) & a_black(s1) & Theme(s1,x2) & n_people(x1) & card_eq_2(x1))
exists e1 e2 x1 x2 x3 x4 x5.(behind(e1,x3) & Theme(e2,x5) & Actor(e2,x4) & v_serve(e2) & n_lunch(x5) & (x3 = x4) & n_counter(x3) & Actor(e1,x1) & v_stand(e1) & in(x1,x2) & n_hat(x2) & n_people(x1) & card_eq_2(x1))