thinkphpのselectとfindの違い

$tech=M('techlevel','HR_CS_','DB_CONFIG2');
$Data=$tech->where('id=1')->find();
dump($Data);
$Data=$tech->where('id=1')->select();
dump($Data);

array(6) {
  ["ID"] => int(1)
  ["TechLevel"] => string(2) "10"
  ["Remark"] => string(4) "??"
  ["CreateDate"] => string(19) "2013-03-14 15:14:38"
  ["CreateBy"] => string(5) "admin"
  ["ROW_NUMBER"] => string(1) "1"
}

array(1) {
  [0] => array(6) {
    ["ID"] => int(1)
    ["TechLevel"] => string(2) "10"
    ["Remark"] => string(4) "??"
    ["CreateDate"] => string(19) "2013-03-14 15:14:38"
    ["CreateBy"] => string(5) "admin"
    ["ROW_NUMBER"] => string(1) "1"
  }
}