Difference between $watch expressions in directive link vs controller function?

Question

I've seen this done both ways; What is the difference between creating a scope.$watch in a directive controller vs the linking function?

Answer 1

There is no real difference between the two. At the matter of fact, the $watch expression will be accessible from both the controller and the directive regardless to where it was initially defined, as they both share the same $scope. That being said, a $watch in defined in the directive has a completely different purpose than a one defined in the controller.

Answer 2

There is no difference as far as I can tell. The scope passed in the linking is: "Scope - The scope to be used by the directive for registering watches."

So if you don't explicitly declare a controller or scope for the directive you still have a scope (taken from the context in which the directive is being compiled) to add watches to in the link function returned by the compile.