WebPush PushSubscription vs messaging.getToken?

Question

JavaScript

Good afternoon.
I implement a subscription for push notifications on the site.
I can't figure out the difference between the two approaches.
The first one is just to get a token and send it to the server, then send messages referring to it

function subscribe() {
  // запрашиваем разрешение на получение уведомлений
  messaging.requestPermission()
    .then(function () {
      // получаем ID устройства
      messaging.getToken()
        .then(function (currentToken) {
          console.log(currentToken);

          if (currentToken) {
            sendTokenToServer(currentToken);
          } else {
            console.warn('Не удалось получить токен.');
            setTokenSentToServer(false);
          }
        })
        .catch(function (err) {
          console.warn('При получении токена произошла ошибка.', err);
          setTokenSentToServer(false);
        });
    })
    .catch(function (err) {
      console.warn('Не удалось получить разрешение на показ уведомлений.', err);
    });
}

The second is to get the PushSubscription object and use what it returned to send messages

function subscribeUserToPush() {
  return navigator.serviceWorker.register('service-worker.js')
  .then(function(registration) {
    var subscribeOptions = {
      userVisibleOnly: true,
      applicationServerKey: btoa(
        'BEl62iUYgUivxIkv69yViEuiBIa-Ib9-SkvMeAtA3LFgDzkrxZJjSgSnfckjBJuBkr3qBUYIHBQFLXYp5Nksh8U'
      )
    };

    return registration.pushManager.subscribe(subscribeOptions);
  })
  .then(function(pushSubscription) {
    console.log('PushSubscription: ', JSON.stringify(pushSubscription));
    return pushSubscription;
  });
}

{
  "endpoint": "https://domain.pushservice.com/some-id",
  "keys": {
    "p256dh":
"BIPUL12DLfytvTajnryr3PJdAgXS3HGMlLqndGcJGabyhHheJYlNGCeXl1dn18gSJ1WArAPIxr4gK0_dQds4yiI=",
    "auth":"FPssMOQPmLmXWmdSTdbKVw=="
  }
}