The C SDK is the basis for ThingWorx Edge SDKs and the Edge MicroServer (EMS). You can compile C SDK applications on any platform and even run it without an operating system. Using the C SDK for your application means least amount of RAM, processing power, and disk space, frequently requiring less than 200 kilobytes. The C SDK is also the only SDK that is distributed as source code.
The Java SDK is especially useful if you are integrating with an application that uses a Java-based API. While applications based on the Java SDK tend to use more RAM, processing power, and disk space than a C SDK equivalent application, they typically take less time to develop. To use it, you will need a platform with a supported Java Virtual Machine. The Java SDK support Android development.