It al depends on two things.


1 - The type of gig

2 - The type of audience


If you are performing in a club, frequented by folkies then it can be termed a folk session, hootenany or whatever - BUT -
if you are in a pub/club where oly a portion of the audience are there for the music and the songs,and the remainder are there for drinks, conversation, laughs or whatever then it is show business.