You should have put Aruba and Curacao under Netherlands as well because they are both territories of the Netherlands. Also, would the United Kingdom count because the Cayman Islands are South West of Cuba therefore they are closer? (And yes, the United Kingdom owns the Cayman Islands.)
Cayman Islands would be too far away, 1094 km / 681 miles, anyway. To answer your question, there is a different relationship between the UK and its territories, and between the constituent countries of the Netherlands. For a start, UK territories do not form a part of the UK. Secondly, the country of the Netherlands, Sint Maarten, Curaçao and Aruba are four constituent countries that comprise the Kingdom of the Netherlands (it's a bit confusing that there's a country of the Netherlands, and a Kingdom of the Netherlands, that are not the same, but there you go). To make it more confusing still, the country of the Netherlands has four parts, the large, famous part in mainland Europe with Amsterdam etc on it, plus three other parts in the Caribbean: Bonaire, Sint Eustatius and Saba.