Multi-threading is all about multiple workers where as Asynchronous is making multiple tasks by single worker.
In Real world example lets take an example of a star hotel.
Multi-Threading example: In a star hotel for each and every table a single waiter will be assigned to take the order and deliver the food.
Asynchronous example: In a star hotel for a section of tables will be assigned by single waiter and for delivering the order one another waiter will be assigned.
So here in asynchronous process either waiter will wait until the order details are provided by customer or else he can give the menu to table1 and he can also visit the other table he can give the menu to table 2 also.
In terms of this real world star hotel example in asynchronous process waiter is working multiple tasks at the same time, Where as in multi threading multiple waiters or resources will be utilized which will also impact performance.
