Different kind of Angular Directives patterns

angular.directive('ppd:reset', function(e1,e2) {
    return function(linkElement) {      
        linkElement.wrap()....
        });
    };
});

And

angular.directive('ppd:reset', [function() {
        return function(scope, elm, attrs) {   } 

}]);

What is the difference between these two directives pattern ?