loose interface vs abstract in php

intefaceabtract

interface Mail {
   public function sendMail();

   public function getFuel();

}
abstract class MyAbstractClass implements Mail {
   function myAbstractFunction() {
    echo "not abstract";
   }
   
   public function sendMail(){
   	echo 9;
   }
   
}
class DetailClass extends MyAbstractClass {
  function getFuel() {
  	echo 'finally get fuel';
  }
}
$ok = new DetailClass();
$ok->getFuel();