Java is confusing too so being just like Java doesn't mean it's easy to understand. (Do I need the Java runtime environment, the SDK or the browser extensions to run this code?)
That's really only half of it; Java is also a programming language, a bytecode spec, and a binary executable that sometimes points to a JRE and sometimes refers to a JDK, depending on how you installed it. Arguably it's also now being used to refer to the API of the standard library too.
> Do I need the Java runtime environment, the SDK or the browser extensions to run this code?
It's not really confusing.
The Runtime is required to run code. The Source Development Kit (SDK) is for development, and the Browser Extension is for running browser extensions.