Well a lot of accordion music sounds stylistically similar, particularly when played on the big continental chromatic jobbies - the ones with acres of buttons on both sides- but that's the nature of the beast. I think the 'French bistro' music you are looking for is probably what is called Style (pronounced steel) Musette which means Bagpipe Style and is particular associated with Paris. It originated from the interplay of Auvergnat bagpipe players and Italian accordion players in the bars and dance-halls of late 19C Paris and is now played almost solely on accordion.