Collection is an interface in Java.
But Collections is a class in Java.
Collection is a base interface. 
Collections is a utility class in Java.
Collection defines methods that are
used for data structures that contain the objects. 
Collections define the methods that are used 
for operations like access, find, etc. on a Collection.
Collection Interface has only abstract
methods but Collections consists of 
only static methods that are used to
operate on objects of type Collection.