- Subtyping refers to compatibility of interfaces. A type B is a subtype of A if every function that can be invoked on an object of type A can also be invoked on an object of type B.
- Inheritance refers to reuse of implementations. A type B inherits from another type A if some functions for B are written in terms of functions of A.
- Integer is a subtype of Number
ArrayList<E> is a subtype of
- String is a subtype of Object