None.
Sun simply changed the name from JDK (Java Development Kit) to Java SDK (Software Development Kit). However, it hasn't caught on with most developers, who are used to calling the SDK by its original name, JDK. Keep in mind, though, that there are different versions, but that's all.
>Hello everyone!
>
>What's the diference between JDK and SDK.?
>
>Sergio
Andres M. Chiriboga, MCSE, MCP+I