In an interface class, all methods are abstract - there is no implementation.  In an abstract class some methods can be concrete.  In an interface class, no accessibility modifiers are allowed.  An abstract class may have accessibility modifiers.

(If you ask this question, be sure you have some concrete experience in this area.)

(This question can be made more perceptive if you actually have some concrete suggestions for monetary as well as nonmonetary methods for recognizing performance. Who knows, you may end up on the receiving end of what you suggest.)

Aggregate tables are pre-computed totals in the form of hierarchical mutidimensional structure.,whereas materliazed view is the database object which caches the query result in a concrete table and updates it from the original database table from time to time .Aggregate tables are used to speed up the query computing whereas materialized view speed up the data retrieval .

A concrete class is used to define a useful object that can be instantiated as an automatic variable on the program stack. The implementation of a concrete class is defined. The concrete class is not intended to be a base class and no attempt to minimize dependency on other classes in the implementation or behavior of the class.