mysql_fetch_assoc
    The function returns an associative array of strings that corresponds
    to the fetched row, or FALSE if there are no more rows.
    The associativity array tells us about the key value pair,
    whereas the key tells about any column name and the value tells 
    about the row value.

    Here we can map the column name as key and value as row. For example.
    Key is ID and value is corresponding name.

mysql_fetch_array

  This function name suggests that it returns an array.
  It fetches a result row as an associative array, a 
  numeric array, or both. It has both numeric values as 
  well as string values for a key.

mysql_fetch_object
This function returns row as an object and does not return an array.