If we create the threads the execution of those threads that will take care time schedule it’s all done by thread scheduler if the thread scheduler is taking help from only jvm not from OS then those thread is called GreenThread.
If thread wants to execution then it needed help from 2 1 from JVM and one is OS then if thread taking help from those 2 then it’s called native OS thread non green thread and if thread taking one of the help like it only takes help from the JVM not from OS then it’s called Green Thread.