With the latest version of the studio (SDK), the name, the build strategy and the release numbers changes.
Let me start with the last point.
As of 2013 SAP´s cloud products (ByDesign, Customer OnDemand, SuccessFactors products) share common release number that consist of year and month (YYMM), for example 1302 and 1305. For ByDesign, 1302 is the successor of ByDesign 4.0.
As of version 1302, there is only one joined build of the Studio for ByDesign, Customer OnDemand and additional supported cloud products (see figure, below). So, if you work for ByDesign and Customer OD, you have to install only one frontend instead of two.
As a consequence, we had to find a common name for the studio – the new name is SAP Solutions OnDemand Studio.
Finally I want to answer the question, does a joined build for ByDesign and Customer OD mean that the same content types are available for ByDesign and Customer OD (and for other products)? The answer is: In general yes, but there are still differences. The most important ones are that thing-based UIs are not supported in ByDesign and scalable solutions are not supported for Customer OD. You can find the detailed information on the features in the Feature Matrix in the documentation, see What's New in SAP Solutions OnDemand Studio Version February 2013 (1302) or https://help.sap.com/studio_od.
The SAP Solutions OD Studio 1302 is now available on the Service Marketplace, http://service.sap.com/swdc -> Search for Software Downloads, Search Term "SAP SOLUTIONS OD STUDIO 1302".