A male with a beard is playing a guitar.
A musician demonstrates his skills with the guitar.
While the male is playing a guitar it does not indicate that he is a skilled musician that demonstrates his skills. He could be someone that knows nothing about guitars or music and just picked it up to play around with it.
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & n_guitar(x3) & with(x1,x2) & n_beard(x2) & n_male(x1))
exists e1 x1 x2 x3.(n_guitar(x3) & with(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_demonstrate(e1) & n_skill(x2) & of(x2,x1) & n_male(x1) & n_musician(x1))