What's the difference? Surely just two different variations in spelling of the same place? Not a good assumption to make if you happen to be booking flights there on the Internet as one is a small island located in the Grenadines, located just off the north coast of Venezuela whereas the other was once a 'Royal' city and capital of the Moorish part of Spain and home to the 'Alhambra', a masterful example of Islamic
The art of getting a quote that is both competitive in price and relevant to your needs starts with gathering all the right information about what you want to do (or think you want to do!).