If the question is asked in BelgiumIn this context, savoir jouer means being knowledgeable in guitar playing while pouvoir jouer means that would be:nothing prevents the person from playing the guitar.
Marc, tu sais jouer de la guitare, non ?
and it will make no distinction between theWhat might prevent Marc from playing can be either a physical ability /psychological limitation or some external constraint (pouvoir in Franceprohibition) and.
Here are the learned skill,various cases:
> *Marc, tu sais jouer de la guitare ?*
A. Have you learn how to play the knowledgeguitar (savoirare you a skilled guitarist)?
> *Marc, tu peux jouer de la guitare ?*
B. Is a personal limitation/disability preventing you to play the guitar?
The questionC. Are you allowed to play the guitar?
Pouvoir can also be used to politely ask someone to do something:
Marc, tu peux jouer de la guitare, non ?Marc, tu peux jouer de la guitare, s'il te plait ?
would only make sense there if we suspect that for some reason Marc has been prohibited fromD. Would you mind playing the guitar, please?
Note that if the question is asked in Belgium, *savoir* would be used for A., B. and D. and *pouvoir* would only be used for C.
e.g.
Marc, tu sais jouer de la guitare, s'il te plait? (D.)