Difference between task and function

To reuse the same lines of code again and again methods are used. System Verilog supports two types of methods.
(1) Function
(2) Task

Function:
- Delayed can NOT use in the function.
- Task WITHOUT delay can call in the function. It shouts only WARNING, not an ERROR.
- The function calls another function.
- The function can return value.

Task:
- Delayed can be inserted in the task.
- The task with DELAY can be called in the task.
- The function also can call in the task.
- The task can NOT return value.

The user can NOT call a task in function. Is it true? Is it shouts an ERROR?
NOT ALWAYS. The user can call a task in function if the definition of a task should NOT contain delay.

WITHOUT delay Warning: "warning-[teif] Task enabled inside a function"

WITH delay Error: "Function "function_name" has illegal use of delay or synchronization"


USER WANT CODE:

function hello();

  $display("This is Hello function");

  Hi(); // CALL TASK(without delay) INSIDE FUNCTION

endfunction

task Hi();

  //#1;  // without delay

  $display("This is Hi task");

  hello();

endtask

module top();

initial

   begin

     hello(); // Call function

     //Hi(); // call task

   end

endmodule

To run simulation click on below link:
Link: https://www.edaplayground.com/x/2uZ8