The first declaration defines the function within a scope, could be Global, and allows you to call that function from within that context but the values or variables within the function don't change unless they reference a parameter or another Global value.
The difference is that the second function declaration can be used within another function to use in, for example, a Promise or as parameter and is subject to Closure. You can use this type of declaration for functions that depend on values or variables
that are dynamic on some context, for example:
//reading some random data from a webpage with WinJS.xhr
function ReadData(someUrl){
var handler = function(result){
//read the data from the result.responseText
console.log(someUrl+" > readed data: "+result.responseText);
}
WinJS.xhr({url:someUrl}).done(handler);
}
When the "handler" dynamic function is created, it contains the value of "someUrl", once the xhr is finished getting the contents of the site (for ex. "http://www.microsoft.com") it displays its raw content plus the value of the "someUrl" parameter. If you
call the function with a different parameter, the "handler" will be created dynamically with the new value.
Trying to accomplish this with a Globally declared function would be quite harder.
