What is difference between aggregation versus generalization ?(C++)

Aggregation is not same thing as generalization Aggregation relates instances. Two distinct objects are involved, one of them is part of the other. Generalization relates classes and is a way of structuring the description of a single object. Both super-class and sub-class refers to properties of a single object with generalization, an object is simultaneously an instances of the super-class and an instances of sub-class. Confusion arises because both aggregation and generalization give rise to trees through transitive closure. An aggregation tree  is composed of object instances that are all part of a composite object a generalization tree is composed of a classes that describes the object Aggregation is often called “a-part of” relationship; generalization is often called “a-kind of” or “is-a” relationship.