what is bytecode and machine code , what is the difference ?

Answer 1

in jvm,it is no code such as utf-8,gbk and so on,so it use unicode,but because java can run in different os,so it would change to os code,such as utf-8,gbk

Answer 2

bytecode are those 0s and 1s, isn't it?
machine code iimg wu answered. it is already the codes we see.