Comparison of Object and Relational Terminology
This figure presents a comparison of some basic terms used in relational and object technology. New technology, in this case object technology, often creates new terms to go with the new technology. There are similarities and differences between relational and object technology. For example, a relation is similar to a class. Yet, a relation does not have the concept of inheritance that is found with a class. A tuple is similar to an instance object. Yet, a tuple is limited to the data structure it can hold. An instance object can handle any data structure supported by C++ or Java. A column is similar to an attribute. Yet, a column is limited to certain data types. An attribute can hold any C++ or Java data type including references to other objects. Finally, a stored procedure is significantly different than a method. Methods are computationally complete because they are written in object programming languages such as C++ or Java. Most stored procedure languages are limited when compared to C++ or Java.
More on the general topic: Comparing Object and Relational Models