Three girls playing football.
Three girls learning how to play football.
Sentence 1 does not clarify what the girls' skill level is while playing football. We have nothing to imply that they are learning how to play football.
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_play(e1) & n_football(x3) & (x1 = x2) & n_girl(x1) & card_eq_3(x1))
exists e1 x1 x2 x3.(a_topic(x1) & Topic(e1,x3) & Actor(e1,x2) & v_learn(e1) & n_manner(x3) & exists e2 x4 x5.(Theme(e2,x5) & Actor(e2,x4) & v_play(e2) & n_football(x5)) & (x1 = x2) & n_girl(x1) & card_eq_3(x1))