While in the search for the various differences in the meanings of source code, bytecode, assembly code, machine code, compilers, linkers, interpreters, assemblers and all the rest, I only got confused on the difference between bytcode and assembly code.
Particularly the introduction this wikipedia article to describe CIL confused me since it seems to use both terms (assembly code and bytecode) interchangeably making me think they might mean exactly the same.
Assembly code normally is used to refer to code that, once compiled to Machine Code, can be executed by a CPU whilst bytecode in a virtual machine.
The source of confusion over CIL might be related to the fact that machine code for CPU X can be interpreted by a Virtual Machine running on CPU Y (for example).
Note that a Virtual Machine implementation can be crafted to interpret any machine code and/or bytecode: it is left to the developers and their aspiration (and time on their hands) ;-)
Assembly code is (represents) the native code for the processor you are programming.
Bytecode is a term for the binary version of the "commands" that are compiled to be executed by an interpreter, or a virtual machine.
In essence bytecodes define the opcodes for a virtual processor, while assembly consists of the opcodes of a physical processor. (we will ignore the microcode inside the CPU for now :-) )
assembler is a macro language. It's a set of instructions used to instruct the CPU or other device. It's translated in machine code which are readable instructions by the CPU.
Byte code s are instructions for the virtual machine to be interpreted and still need to get translated into machine code before being executed.
Assembly code normally does mean the human readable form of a machine's native language (the so called machine language). Byte code on the other hand is normaly a language that can be interpreted by a byte code interpreter -- so it is not the processors native language.
Why the confusion then? You can't compare Assembly language versus Byte code this way. Of course a byte code can also have an assembly code -- meaning an human readable form of it, because "Assembly language" does not necessary mean that it is for a real machine -- but it is a human readable form of some native language -- for processors, this native language is the machine code -- but you also can have assembly code of a pseudo-(or interpreted) machine like Bytecode.
See also: Assembly Language
Further distress comes of course -- like you can see in all the discussion here -- because IT people (also myself) tend to be lax in wording. "Assembly language" is often used when speaking about machine code. This of course is not totally correct, because Assembly Language is only the human readable form of some machines code.
Assembled code is runnable on a CPU with a specific instruction set, while bytecode can be executed in a virtual machine (such as the Java runtime) on any CPU that can run the VM.