Difference between forward and tell in akka actors

Question

What is a difference between tell and forward, in case I will send the same message:

case msg: Message =>
  otherActor tell (msg,sender)

and

case msg: Message =>
  otherActor forward msg

Solution 1

The sender() will be different on the receiving end.

Message sends using tell (also known as !):

A tells message M to B.
B tells that message to C.
C thinks the sender() of message M is B.

Message sends using forward:

A tells message M to B.
B forwards that message to C.
C thinks the sender() of message M is A.

Worth pointing out is, that you can achieve the same as forward when explicitly setting the sender of a message using tell, however this is not typical Akka-style:

// inside `B`, when received `msg` from `A`
C tell (msg, A) 
      == 
C forward msg

For more info refer to the docs about forward.

Solution 2

Tell sets the sender as the actor sending the message.

Forward keeps the original sender of the message.

Solution 3

target.tell(message, getSelf()); final Object result = ""; target.forward(result, getContext());

Here, getself() is the self reference of the actor. getcontext() is the supervisor reference.