Set<String> sStrings = new Set<String>{'a','b','c','d','e'};

List<String> lStrings = new List<String>(sStrings);

​

Set<String> setStrings = new Set<String>{'hello','world'};

List<String> listStrings = new List<String>(setStrings);

Set<String> sStrings = new Set<String>{'a','b','c','d','e'};

List<String> lStrings = new List<String>();

lString.addAll(sStrings);