In push queues, tasks are thrown to your application, in pull queues, you would have to fetch tasks yourself.

Because tasks are pushed to your application, Google App Engine takes care of scaling as well. New machine instances will be started when there's more load than a single instance can handle. And all that happens automatically. In case of pull queues, you are responsible for the scaling part yourself.

When a task gets successfully executed in a push queue, it is automatically deleted by Google App Engine with no effort at your end. In case of pull queues, you have to do that yourself as well.

In push queues, you are limited to the Google App Engine environment as your task handling code must be mapped to URLs within your application. In contrast, in the case of pull queues, because the tasks are pulled they can be pulled from anywhere such as a machine...