Answer:   Thread represents an actual OS-level thread, with its own stack and kernel resources, and allows the highest degree of control. You can choose to Abort() or Suspend() or Resume() a thread, and set thread-level properties, like the stack size, apartment state, or culture. While a Task class from the Task Parallel Library is executed by a TaskScheduler to return a result and allows you to find out when it finishes.

Answer:   1) Task is more abstract then threads. It is always advised to use tasks instead of thread as it is created on the thread pool which has already system created threads to improve the performance.

2) The task can return a result. There is no direct mechanism to return the result from a thread.

3) Task supports cancellation through the use of cancellation tokens. But Thread doesn't.

4) A task can have multiple processes happening at the same time. Threads can only have one task running at a time.