List:
    List is a ordered collection of values. It contains duplicate values. Each value is retrieved using the List Index.


Ex: 
List<String> temp = new List<String>();
temp.add(‘Newyork’);
temp.add(‘Miami’);

temp.add(‘Boston’);

Set:
    Set is an unordered collection of values. It does not contains duplicate values.


Map:
    Map is a key value pair datatype.

Ex:

Country (Key)	‘United States‘	‘England‘	‘India‘	‘Japan‘	‘France‘
Currency (Value)	‘Dollar’	‘Pound’	‘Rupee’	‘Yen’	‘Euro’