Details of the differences between fetchAll of and mysql_fetch_array of

The same query statement:
fetchAll () :

array(1) {        
   [0]=>  array(6) {              
     ["id"]=>    string(2) "15"           
                   [0]=>    string(2) "15"         
            ["lot_sellid"]=>    string(20) "00000000000000003877"     
     [1]=>    string(20) "00000000000000003877"               
      ["lotteryid"]=>    string(2) "D8"                
            [2]=>    string(2) "D8"                  
        }   
}

mysql_fetch_array():

array(6) { 
                      [0]=> string(2) "15" 
                      ["id"]=> string(2) "15" 
                      [1]=> string(20) "00000000000000003877" 
                      ["lot_sellid"]=> string(20) "00000000000000003877" 
                      [2]=> string(2) "D8" 
                      ["lotteryid"]=> string(2) "D8"  
}