//array_diff_uassoc for multidimenssional array$color_1=array('a'=>'white','b'=>'red','c'=>array('a'=>'green','b'=>'blue','c'=>'yellow'));$color_2=array('a'=>'white','b'=>'red','c'=>array('a'=>'white','b'=>'red','c'=>'yellow'));function key_compare($a,$b){ if($a===$b) return 0; return($a>$b)?1:-1;}print_r(array_diff_uassoc($color_1['c'], $color_2['c'],"key_compare"));//Output Array( [a] => green [b] => blue)