A young man is playing a blue guitar.
A musician practices on his guitar briefly before a concert.
this young man could play the guitar without being a concert musician
It is not necessary for man to be a musician to play guitar. Playing guitar doesn't necessarily mean doing practice on guitar. A young man is playing a blue guitar doesn't imply that he is practicing on his guitar briefly before a concert.
Just because the man is playing a guitar does not mean that he is a musician.