The taste of the grapes. ve The grape's taste. ve I don't know the city's mayor./ I don't know the mayor of the city. arasındaki fark nedir?Sadece örnek cümleler vermekten çekinmeyin.

I would use the former in both scenarios. The latter are correct, but strange because there is not really possession. When taking about someone in a position of political power, "of" is used almost exclusively: "Wallis, duchess of Windsor, would like another cup of tea." "The mayor of the city passed away earlier today of unknown causes."

In terms of the grapes, "the taste of the grapes" is better than "the grapes' taste" mostly because the latter sounds exactly like "the grapes taste..." which can be confusing and take longer to process.

P.S. "The taste of the grapes" = "the grapes' taste" not "the grape's taste"

"the grape's taste" = "the taste of the grape"