byte_code_vs_machine_code.txt

"Byte code" refers to data that can be executed by a virtual machine. 
The virtual machine takes the byte code and produces machine code appropriate for the actual machine it is running on.
Machine code or machine language is a system of instructions and data directly executed by a computer's central processing unit. 

Since byte code is processed by software, it is usually more abstract than machine code.It's an abstraction for portability.
Machine code is the lowest-level of abstraction for representing a computer program. 

Machine code is machine specific, bytecode is system-independent. It is rather VM specific and runs on all supported architectures

Advantages and disadvantages:
Bytecode is shorter, more precise and more readable.
Every CPU model has its own machine code, or instruction set.
 
At run-time Bytecode  is mostly slower than optimized machine code.
Even if JIT is used to convert bytecode to machine-code,more  time and space is needed to do that.