Why two sentences? Maybe you should ask ChatGPT if you want explanations with specific length requirements.
Anyway it's pretty simple really. A generic thread is bunch of stack frames (with their associated local variables). A standard OS thread is under the control of the kernel scheduler which decides whether the thread runs and makes progress or not. The VirtualThread in Java is just a thread which is not directly mapped to the OS thread scheduler but exists as a user space object that can be scheduled by a (Java implemented) scheduler. It's basically just a call stack with its local variables, but one that only steps forward when an OS thread of the scheduler decides to step it.
Anyway it's pretty simple really. A generic thread is bunch of stack frames (with their associated local variables). A standard OS thread is under the control of the kernel scheduler which decides whether the thread runs and makes progress or not. The VirtualThread in Java is just a thread which is not directly mapped to the OS thread scheduler but exists as a user space object that can be scheduled by a (Java implemented) scheduler. It's basically just a call stack with its local variables, but one that only steps forward when an OS thread of the scheduler decides to step it.