[great_psy]

I have not delved to deep in the code, but is there any functional differences it has over Java other than the size ?

Presumably Java would also be pretty tiny if we wrote it in bytecode instead of higher lever Java.

[teraflop]

The Java bytecode instruction set actually has a quite complicated specification: https://docs.oracle.com/javase/specs/jvms/se8/html/

Which means implementations also have to be correspondingly complicated. You have to handle quite a few different primitive data types each with their own opcodes, class hierarchies, method resolution (including overloading), a "constant pool" per class, garbage collection, exception handling, ...

I would expect a minimal JVM that can actually run real code generated by a Java compiler to require at least 10x as much code as a minimal Bedrock VM, and probably closer to 100x.