The "DB2 is DB2 are DB2" is true for distributed platforms running IBM DB2 Universal Database, and for various versions that can be purchased.
The easy way to remember is to have nothing to worry about when you need to upgrade. It means that for zseres servers running on any of the distributed platforms supported by DB2 (Windows, HP-UX, Sun Solaris, Linux-iseries, Pseries, xseries, aix®, and DB2), you write for DB2 any Applications can run on these platforms. In fact, here's a cross-family SQL Reference book, which allows developers to write portable applications across product families in a common SQL language. This means that applications written for DB2 on Windows can easily be ported to DB2 on z/os™. To further enhance the DB2 family value orientation (value proposition), you can use products such as WebSphere information integrator to extend the DB2 SQL API so that it can transparently access non-IBM relational databases (for example such as Oracle or SQL Server, the product can also be materialized into relational tables from non relational data sources such as XML streams, message queues, VSAM, IMS, and so on, to create a truly corporate-level public data model. Indeed, DB2 allows access to them wherever the data is located.
There are different versions of DB2. DB2 versions actually differ only in packaging and licensing, and they attempt to allocate the appropriate features, functionality, and benefits of a DB2 solution to the right market. The various versions of DB2 allow users to pay custom prices for the special features they need. Of course, the underlying technology has always been DB2, so the decision about which version to use has nothing to do with portability, usability, and usability. In addition, if you write an application for DB2 Personal Edition (DB2 PE), the application will be available in DB2 Express, DB2 Workgroup Server Edition (DB2 WSE), DB2 workg Roup Server Unlimited Edition (DB2 wsue) and DB2 Enterprise server Edition (DB2 ESE) are running on these versions.
Typically, customers (and IBM personnel in this area) need to have a quick and easy place to compare the differences between the licensing rules, features, and functionality included in the Distributed DB2 Server family. In this article, I used a simple table to compare and contrast the different DB2 server versions of the DB2 V8.2.3 release (around September 2005), for some of the most common issues I learned from customers, such as what to use. (This article also includes some side notes about the changes between the DB2 version 7 release and the DB2 version 8 release.)
However, this article and the table attached below may not be complete. This article tries to answer 80% of the questions I've heard during conversations with customers or meetings (if I don't talk about your question, email me so I can add it in future updates). The distributed DB2 family is actually like a Russian doll--the features in one version are available in other versions, but the feature I'm talking about here is an exception. In other words, in most cases, I'm not going to talk about the features that are common and can be licensed in the same way on all platforms. For example, any distributed DB2 Server version includes sql-based replication capabilities, so it is not mentioned in the following table.