What is the different between Interface Collection and Class Collection ?

Thanks for those people help me to answer

There is a class called Collections no Collection .Collections can carry different types of Collection which is the generic java interface . (Like arrayList ,List ,Tree ) .

An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior and all methods are implicitly abstract. An interface has all public members and no implementation. An abstract class is a class which may have the usual flavors of class members (private, protected, etc.), but has some abstract methods.